661863788 has 48 divisors (see below), whose sum is σ = 1268646624. Its totient is φ = 300917760.

The previous prime is 661863757. The next prime is 661863833. The reversal of 661863788 is 887368166.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 240098 + ... + 242838.

It is an arithmetic number, because the mean of its divisors is an integer number (26430138).

Almost surely, 2^661863788 is an apocalyptic number.

661863788 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

661863788 is a deficient number, since it is larger than the sum of its proper divisors (606782836).

661863788 is a wasteful number, since it uses less digits than its factorization.

661863788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2882 (or 2880 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 53.

The square root of 661863788 is about 25726.7135095021. The cubic root of 661863788 is about 871.4775561259.

The spelling of 661863788 in words is "six hundred sixty-one million, eight hundred sixty-three thousand, seven hundred eighty-eight".