642791690 has 16 divisors (see below), whose sum is σ = 1160346600. Its totient is φ = 256378560.

The previous prime is 642791689. The next prime is 642791701. The reversal of 642791690 is 96197246.

It can be written as a sum of positive squares in 4 ways, for example, as 601279441 + 41512249 = 24521^2 + 6443^2 .

It is a super-2 number, since 2×642791690² = 826362313466112200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88601 + ... + 95580.

Almost surely, 2^642791690 is an apocalyptic number.

642791690 is a deficient number, since it is larger than the sum of its proper divisors (517554910).

642791690 is a wasteful number, since it uses less digits than its factorization.

642791690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184537.

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 642791690 is about 25353.3368612496. The cubic root of 642791690 is about 863.0250822162.

The spelling of 642791690 in words is "six hundred forty-two million, seven hundred ninety-one thousand, six hundred ninety".