520400661 has 16 divisors (see below), whose sum is σ = 762912768. Its totient is φ = 312908400.

The previous prime is 520400641. The next prime is 520400681. The reversal of 520400661 is 166004025.

It is an interprime number because it is at equal distance from previous prime (520400641) and next prime (520400681).

It is not a de Polignac number, because 520400661 - 2²⁷ = 386182933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520400611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57895 + ... + 66276.

It is an arithmetic number, because the mean of its divisors is an integer number (47682048).

Almost surely, 2^520400661 is an apocalyptic number.

It is an amenable number.

520400661 is a deficient number, since it is larger than the sum of its proper divisors (242512107).

520400661 is a wasteful number, since it uses less digits than its factorization.

520400661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124312.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 520400661 is about 22812.2918839822. The cubic root of 520400661 is about 804.3516304914.

Adding to 520400661 its reverse (166004025), we get a palindrome (686404686).

The spelling of 520400661 in words is "five hundred twenty million, four hundred thousand, six hundred sixty-one".