642776831 has 2 divisors, whose sum is σ = 642776832. Its totient is φ = 642776830.

The previous prime is 642776807. The next prime is 642776843. The reversal of 642776831 is 138677246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642776831 - 2¹⁸ = 642514687 is a prime.

It is a super-2 number, since 2×642776831² = 826324108940805122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642776531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321388415 + 321388416.

It is an arithmetic number, because the mean of its divisors is an integer number (321388416).

Almost surely, 2^642776831 is an apocalyptic number.

642776831 is a deficient number, since it is larger than the sum of its proper divisors (1).

642776831 is an equidigital number, since it uses as much as digits as its factorization.

642776831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 44.

The square root of 642776831 is about 25353.0438212062. The cubic root of 642776831 is about 863.0184321673.

The spelling of 642776831 in words is "six hundred forty-two million, seven hundred seventy-six thousand, eight hundred thirty-one".