661465720 has 16 divisors (see below), whose sum is σ = 1488297960. Its totient is φ = 264586272.

The previous prime is 661465621. The next prime is 661465771. The reversal of 661465720 is 27564166.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 661465720.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8268282 + ... + 8268361.

Almost surely, 2^661465720 is an apocalyptic number.

It is an amenable number.

661465720 is an abundant number, since it is smaller than the sum of its proper divisors (826832240).

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

661465720 is a wasteful number, since it uses less digits than its factorization.

661465720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16536654 (or 16536650 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 661465720 is about 25718.9758738563. The cubic root of 661465720 is about 871.3028087409.

The spelling of 661465720 in words is "six hundred sixty-one million, four hundred sixty-five thousand, seven hundred twenty".