638751973 has 2 divisors, whose sum is σ = 638751974. Its totient is φ = 638751972.

The previous prime is 638751947. The next prime is 638751983. The reversal of 638751973 is 379157836.

638751973 is nontrivially palindromic in base 11.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637411009 + 1340964 = 25247^2 + 1158^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638751973 is a prime.

It is a super-2 number, since 2×638751973² = 816008166022785458, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638751983) 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, 319375986 + 319375987.

It is an arithmetic number, because the mean of its divisors is an integer number (319375987).

Almost surely, 2^638751973 is an apocalyptic number.

It is an amenable number.

638751973 is a deficient number, since it is larger than the sum of its proper divisors (1).

638751973 is an equidigital number, since it uses as much as digits as its factorization.

638751973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 952560, while the sum is 49.

The square root of 638751973 is about 25273.5429451432. The cubic root of 638751973 is about 861.2133463645.

The spelling of 638751973 in words is "six hundred thirty-eight million, seven hundred fifty-one thousand, nine hundred seventy-three".