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388981 = 3710513
BaseRepresentation
bin1011110111101110101
3201202120201
41132331311
544421411
612200501
73210025
oct1367565
9652521
10388981
1124627a
12169131
13108088
14a1a85
157a3c1
hex5ef75

388981 has 4 divisors (see below), whose sum is σ = 399532. Its totient is φ = 378432.

The previous prime is 388963. The next prime is 388991. The reversal of 388981 is 189883.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 189883 = 317599.

It can be written as a sum of positive squares in 2 ways, for example, as 133956 + 255025 = 366^2 + 505^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-388981 is a prime.

It is a super-2 number, since 2×3889812 = 302612436722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 10513 = 388981 / (3 + 8 + 8 + 9 + 8 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 388981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (388901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5220 + ... + 5293.

It is an arithmetic number, because the mean of its divisors is an integer number (99883).

2388981 is an apocalyptic number.

It is an amenable number.

388981 is a deficient number, since it is larger than the sum of its proper divisors (10551).

388981 is a wasteful number, since it uses less digits than its factorization.

388981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10550.

The product of its digits is 13824, while the sum is 37.

The square root of 388981 is about 623.6834132795. The cubic root of 388981 is about 72.9977481009.

It can be divided in two parts, 388 and 981, that multiplied together give a triangular number (380628 = T872).

The spelling of 388981 in words is "three hundred eighty-eight thousand, nine hundred eighty-one".

Divisors: 1 37 10513 388981