639530491 has 2 divisors, whose sum is σ = 639530492. Its totient is φ = 639530490.

The previous prime is 639530483. The next prime is 639530501. The reversal of 639530491 is 194035936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639530491 - 2³ = 639530483 is a prime.

It is not a weakly prime, because it can be changed into another prime (639530431) 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, 319765245 + 319765246.

It is an arithmetic number, because the mean of its divisors is an integer number (319765246).

Almost surely, 2^639530491 is an apocalyptic number.

639530491 is a deficient number, since it is larger than the sum of its proper divisors (1).

639530491 is an equidigital number, since it uses as much as digits as its factorization.

639530491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 87480, while the sum is 40.

The square root of 639530491 is about 25288.9400924594. The cubic root of 639530491 is about 861.5630897769.

The spelling of 639530491 in words is "six hundred thirty-nine million, five hundred thirty thousand, four hundred ninety-one".