638620531 has 2 divisors, whose sum is σ = 638620532. Its totient is φ = 638620530.

The previous prime is 638620519. The next prime is 638620559. The reversal of 638620531 is 135026836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638620531 - 2²⁷ = 504402803 is a prime.

It is a super-2 number, since 2×638620531² = 815672365229443922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (638620501) 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 as a sum of consecutive naturals, namely, 319310265 + 319310266.

It is an arithmetic number, because the mean of its divisors is an integer number (319310266).

Almost surely, 2^638620531 is an apocalyptic number.

638620531 is a deficient number, since it is larger than the sum of its proper divisors (1).

638620531 is an equidigital number, since it uses as much as digits as its factorization.

638620531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 638620531 is about 25270.9424240569. The cubic root of 638620531 is about 861.1542689891.

The spelling of 638620531 in words is "six hundred thirty-eight million, six hundred twenty thousand, five hundred thirty-one".