521831397 has 4 divisors (see below), whose sum is σ = 695775200. Its totient is φ = 347887596.

The previous prime is 521831389. The next prime is 521831417. The reversal of 521831397 is 793138125.

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 521831397 - 2³ = 521831389 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 (521833397) 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, 86971897 + ... + 86971902.

It is an arithmetic number, because the mean of its divisors is an integer number (173943800).

Almost surely, 2^521831397 is an apocalyptic number.

It is an amenable number.

521831397 is a deficient number, since it is larger than the sum of its proper divisors (173943803).

521831397 is a wasteful number, since it uses less digits than its factorization.

521831397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173943802.

The product of its digits is 45360, while the sum is 39.

The square root of 521831397 is about 22843.6292431829. The cubic root of 521831397 is about 805.0880898419.

The spelling of 521831397 in words is "five hundred twenty-one million, eight hundred thirty-one thousand, three hundred ninety-seven".