646181992 has 8 divisors (see below), whose sum is σ = 1211591250. Its totient is φ = 323090992.

The previous prime is 646181959. The next prime is 646182037. The reversal of 646181992 is 299181646.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 508682916 + 137499076 = 22554^2 + 11726^2 .

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

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40386367 + ... + 40386382.

Almost surely, 2^646181992 is an apocalyptic number.

It is an amenable number.

646181992 is a deficient number, since it is larger than the sum of its proper divisors (565409258).

646181992 is a wasteful number, since it uses less digits than its factorization.

646181992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80772755 (or 80772751 counting only the distinct ones).

The product of its digits is 186624, while the sum is 46.

The square root of 646181992 is about 25420.1099918942. The cubic root of 646181992 is about 864.5397183659.

The spelling of 646181992 in words is "six hundred forty-six million, one hundred eighty-one thousand, nine hundred ninety-two".