642865986 has 36 divisors (see below), whose sum is σ = 1620286902. Its totient is φ = 183675744.

The previous prime is 642865981. The next prime is 642865987. The reversal of 642865986 is 689568246.

It is a happy number.

642865986 is a `hidden beast` number, since 6 + 42 + 8 + 6 + 598 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 476068761 + 166797225 = 21819^2 + 12915^2 .

It is a super-3 number, since 3×642865986³ (a number of 27 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (642865981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 363555 + ... + 365318.

Almost surely, 2^642865986 is an apocalyptic number.

642865986 is an abundant number, since it is smaller than the sum of its proper divisors (977420916).

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

642865986 is a wasteful number, since it uses less digits than its factorization.

642865986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728895 (or 728885 counting only the distinct ones).

The product of its digits is 4976640, while the sum is 54.

The square root of 642865986 is about 25354.8020303847. The cubic root of 642865986 is about 863.0583313710.

The spelling of 642865986 in words is "six hundred forty-two million, eight hundred sixty-five thousand, nine hundred eighty-six".