521387521 has 4 divisors (see below), whose sum is σ = 522564912. Its totient is φ = 520210132.

The previous prime is 521387507. The next prime is 521387551. The reversal of 521387521 is 125783125.

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 521387521 - 2⁷ = 521387393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521387551) 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, 588031 + ... + 588916.

It is an arithmetic number, because the mean of its divisors is an integer number (130641228).

Almost surely, 2^521387521 is an apocalyptic number.

It is an amenable number.

521387521 is a deficient number, since it is larger than the sum of its proper divisors (1177391).

521387521 is a wasteful number, since it uses less digits than its factorization.

521387521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1177390.

The product of its digits is 16800, while the sum is 34.

The square root of 521387521 is about 22833.9116447445. The cubic root of 521387521 is about 804.8597525822.

The spelling of 521387521 in words is "five hundred twenty-one million, three hundred eighty-seven thousand, five hundred twenty-one".