521856440527161 has 4 divisors (see below), whose sum is σ = 695808587369552. Its totient is φ = 347904293684772.

The previous prime is 521856440527157. The next prime is 521856440527187. The reversal of 521856440527161 is 161725044658125.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 521856440527161 - 2² = 521856440527157 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521856440527151) 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, 86976073421191 + ... + 86976073421196.

It is an arithmetic number, because the mean of its divisors is an integer number (173952146842388).

Almost surely, 2^{521856440527161} is an apocalyptic number.

It is an amenable number.

521856440527161 is a deficient number, since it is larger than the sum of its proper divisors (173952146842391).

521856440527161 is a wasteful number, since it uses less digits than its factorization.

521856440527161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173952146842390.

The product of its (nonzero) digits is 16128000, while the sum is 57.

The spelling of 521856440527161 in words is "five hundred twenty-one trillion, eight hundred fifty-six billion, four hundred forty million, five hundred twenty-seven thousand, one hundred sixty-one".