521707621 has 4 divisors (see below), whose sum is σ = 521982252. Its totient is φ = 521432992.

The previous prime is 521707609. The next prime is 521707633. The reversal of 521707621 is 126707125.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (521707609) and next prime (521707633).

It can be written as a sum of positive squares in 2 ways, for example, as 409050625 + 112656996 = 20225^2 + 10614^2 .

It is a cyclic number.

It is not a de Polignac number, because 521707621 - 2²⁵ = 488153189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521704621) by changing a digit.

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, 134446 + ... + 138271.

It is an arithmetic number, because the mean of its divisors is an integer number (130495563).

Almost surely, 2^521707621 is an apocalyptic number.

It is an amenable number.

521707621 is a deficient number, since it is larger than the sum of its proper divisors (274631).

521707621 is a wasteful number, since it uses less digits than its factorization.

521707621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274630.

The product of its (nonzero) digits is 5880, while the sum is 31.

The square root of 521707621 is about 22840.9198807754. The cubic root of 521707621 is about 805.0244304148.

The spelling of 521707621 in words is "five hundred twenty-one million, seven hundred seven thousand, six hundred twenty-one".