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78125 = 57
BaseRepresentation
bin10011000100101101
310222011112
4103010231
510000000
61401405
7443525
oct230455
9128145
1078125
1153773
1239265
1329738
1420685
1518235
hex1312d

78125 has 8 divisors (see below), whose sum is σ = 97656. Its totient is φ = 62500.

The previous prime is 78121. The next prime is 78137. The reversal of 78125 is 52187.

It can be divided in two parts, 7812 and 5, that multiplied together give a triangular number (39060 = T279).

It is a perfect power (a 7-th power), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 77284 + 841 = 278^2 + 29^2 .

It is not a de Polignac number, because 78125 - 22 = 78121 is a prime.

It is a super-2 number, since 2×781252 = 12207031250, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

Its product of digits (560) is a multiple of the sum of its prime divisors (5).

It is a nialpdrome in base 5.

It is a self number, because there is not a number n which added to its sum of digits gives 78125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15623 + ... + 15627.

It is an arithmetic number, because the mean of its divisors is an integer number (12207).

78125 is a Friedman number, since it can be written as (1-8/(5*2))^(-7), using all its digits and the basic arithmetic operations.

278125 is an apocalyptic number.

It is an amenable number.

78125 is a deficient number, since it is larger than the sum of its proper divisors (19531).

78125 is an frugal number, since it uses more digits than its factorization.

78125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35 (or 5 counting only the distinct ones).

The product of its digits is 560, while the sum is 23.

The square root of 78125 is about 279.5084971875. The cubic root of 78125 is about 42.7493986669.

The spelling of 78125 in words is "seventy-eight thousand, one hundred twenty-five".

Divisors: 1 5 25 125 625 3125 15625 78125