521720697 has 4 divisors (see below), whose sum is σ = 695627600. Its totient is φ = 347813796.

The previous prime is 521720681. The next prime is 521720713. The reversal of 521720697 is 796027125.

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 an interprime number because it is at equal distance from previous prime (521720681) and next prime (521720713).

It is not a de Polignac number, because 521720697 - 2⁴ = 521720681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521720197) 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, 86953447 + ... + 86953452.

It is an arithmetic number, because the mean of its divisors is an integer number (173906900).

Almost surely, 2^521720697 is an apocalyptic number.

It is an amenable number.

521720697 is a deficient number, since it is larger than the sum of its proper divisors (173906903).

521720697 is a wasteful number, since it uses less digits than its factorization.

521720697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173906902.

The product of its (nonzero) digits is 52920, while the sum is 39.

The square root of 521720697 is about 22841.2061196426. The cubic root of 521720697 is about 805.0311560283.

The spelling of 521720697 in words is "five hundred twenty-one million, seven hundred twenty thousand, six hundred ninety-seven".