661499868 has 12 divisors (see below), whose sum is σ = 1543499720. Its totient is φ = 220499952.

The previous prime is 661499857. The next prime is 661499893. The reversal of 661499868 is 868994166.

It is a tau number, because it is divible by the number of its divisors (12).

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, 27562483 + ... + 27562506.

Almost surely, 2^661499868 is an apocalyptic number.

It is an amenable number.

661499868 is an abundant number, since it is smaller than the sum of its proper divisors (881999852).

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

661499868 is a wasteful number, since it uses less digits than its factorization.

661499868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55124996 (or 55124994 counting only the distinct ones).

The product of its digits is 4478976, while the sum is 57.

The square root of 661499868 is about 25719.6397330911. The cubic root of 661499868 is about 871.3178020784.

The spelling of 661499868 in words is "six hundred sixty-one million, four hundred ninety-nine thousand, eight hundred sixty-eight".