661565616 has 40 divisors (see below), whose sum is σ = 1710775920. Its totient is φ = 220298496.

The previous prime is 661565609. The next prime is 661565651. The reversal of 661565616 is 616565166.

661565616 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44866 + ... + 57758.

It is an arithmetic number, because the mean of its divisors is an integer number (42769398).

Almost surely, 2^661565616 is an apocalyptic number.

It is an amenable number.

661565616 is an abundant number, since it is smaller than the sum of its proper divisors (1049210304).

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

661565616 is a wasteful number, since it uses less digits than its factorization.

661565616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13973 (or 13967 counting only the distinct ones).

The product of its digits is 194400, while the sum is 42.

The square root of 661565616 is about 25720.9178685365. The cubic root of 661565616 is about 871.3466685518.

The spelling of 661565616 in words is "six hundred sixty-one million, five hundred sixty-five thousand, six hundred sixteen".