521571216021 has 4 divisors (see below), whose sum is σ = 695428288032. Its totient is φ = 347714144012.

The previous prime is 521571216017. The next prime is 521571216031. The reversal of 521571216021 is 120612175125.

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 a cyclic number.

It is not a de Polignac number, because 521571216021 - 2² = 521571216017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521571216031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86928536001 + ... + 86928536006.

It is an arithmetic number, because the mean of its divisors is an integer number (173857072008).

Almost surely, 2^521571216021 is an apocalyptic number.

It is an amenable number.

521571216021 is a deficient number, since it is larger than the sum of its proper divisors (173857072011).

521571216021 is a wasteful number, since it uses less digits than its factorization.

521571216021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173857072010.

The product of its (nonzero) digits is 8400, while the sum is 33.

The spelling of 521571216021 in words is "five hundred twenty-one billion, five hundred seventy-one million, two hundred sixteen thousand, twenty-one".