661358520 has 96 divisors (see below), whose sum is σ = 2229055920. Its totient is φ = 176359680.

The previous prime is 661358519. The next prime is 661358521. The reversal of 661358520 is 25853166.

661358520 is a `hidden beast` number, since 66 + 13 + 585 + 2 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (661358519) and next prime (661358521).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661358521) 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 23 ways as a sum of consecutive naturals, for example, 24301 + ... + 43740.

Almost surely, 2^661358520 is an apocalyptic number.

661358520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661358520 is an abundant number, since it is smaller than the sum of its proper divisors (1567697400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661358520 is a wasteful number, since it uses less digits than its factorization.

661358520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68067 (or 68051 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 661358520 is about 25716.8917250900. The cubic root of 661358520 is about 871.2557371621.

The spelling of 661358520 in words is "six hundred sixty-one million, three hundred fifty-eight thousand, five hundred twenty".