642686431 has 2 divisors, whose sum is σ = 642686432. Its totient is φ = 642686430.

The previous prime is 642686399. The next prime is 642686441. The reversal of 642686431 is 134686246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642686431 - 2⁵ = 642686399 is a prime.

It is a super-2 number, since 2×642686431² = 826091697183035522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642686441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321343215 + 321343216.

It is an arithmetic number, because the mean of its divisors is an integer number (321343216).

Almost surely, 2^642686431 is an apocalyptic number.

642686431 is a deficient number, since it is larger than the sum of its proper divisors (1).

642686431 is an equidigital number, since it uses as much as digits as its factorization.

642686431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 40.

The square root of 642686431 is about 25351.2609351093. The cubic root of 642686431 is about 862.9779720261.

The spelling of 642686431 in words is "six hundred forty-two million, six hundred eighty-six thousand, four hundred thirty-one".