521656 has 16 divisors (see below), whose sum is σ = 986040. Its totient is φ = 258720.

The previous prime is 521641. The next prime is 521657. The reversal of 521656 is 656125.

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

It is a self number, because there is not a number n which added to its sum of digits gives 521656.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521657) by changing a digit.

521656 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1411 + ... + 1741.

2⁵²¹⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

521656 is a deficient number, since it is larger than the sum of its proper divisors (464384).

521656 is a wasteful number, since it uses less digits than its factorization.

521656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534 (or 530 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 521656 is about 722.2575717845. The cubic root of 521656 is about 80.4997878163.

The spelling of 521656 in words is "five hundred twenty-one thousand, six hundred fifty-six".