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21625 = 53173
BaseRepresentation
bin101010001111001
31002122221
411101321
51143000
6244041
7120022
oct52171
932587
1021625
111527a
1210621
139ac6
147c49
15661a
hex5479

21625 has 8 divisors (see below), whose sum is σ = 27144. Its totient is φ = 17200.

The previous prime is 21617. The next prime is 21647. The reversal of 21625 is 52612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 16 + 21609 = 4^2 + 147^2 .

It is not a de Polignac number, because 21625 - 23 = 21617 is a prime.

It is a hoax number, since the sum of its digits (16) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21599 and 21608.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39 + ... + 211.

It is an arithmetic number, because the mean of its divisors is an integer number (3393).

221625 is an apocalyptic number.

21625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21625 is a deficient number, since it is larger than the sum of its proper divisors (5519).

21625 is an equidigital number, since it uses as much as digits as its factorization.

21625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 178 counting only the distinct ones).

The product of its digits is 120, while the sum is 16.

The square root of 21625 is about 147.0544116985. The cubic root of 21625 is about 27.8602732777.

Subtracting from 21625 its sum of digits (16), we obtain a square (21609 = 1472).

It can be divided in two parts, 21 and 625, that added together give a palindrome (646).

The spelling of 21625 in words is "twenty-one thousand, six hundred twenty-five".

Divisors: 1 5 25 125 173 865 4325 21625