661905928 has 8 divisors (see below), whose sum is σ = 1241073630. Its totient is φ = 330952960.

The previous prime is 661905919. The next prime is 661905943. The reversal of 661905928 is 829509166.

It can be written as a sum of positive squares in only one way, i.e., 486555364 + 175350564 = 22058^2 + 13242^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41369113 + ... + 41369128.

Almost surely, 2^661905928 is an apocalyptic number.

It is an amenable number.

661905928 is a deficient number, since it is larger than the sum of its proper divisors (579167702).

661905928 is a wasteful number, since it uses less digits than its factorization.

661905928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82738247 (or 82738243 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 46.

The square root of 661905928 is about 25727.5324895335. The cubic root of 661905928 is about 871.4960510113.

The spelling of 661905928 in words is "six hundred sixty-one million, nine hundred five thousand, nine hundred twenty-eight".