639372869 has 2 divisors, whose sum is σ = 639372870. Its totient is φ = 639372868.

The previous prime is 639372863. The next prime is 639372887. The reversal of 639372869 is 968273936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 579124225 + 60248644 = 24065^2 + 7762^2 .

It is a cyclic number.

It is not a de Polignac number, because 639372869 - 2¹² = 639368773 is a prime.

It is a super-2 number, since 2×639372869² = 817595331226582322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 639372869.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639372863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319686434 + 319686435.

It is an arithmetic number, because the mean of its divisors is an integer number (319686435).

Almost surely, 2^639372869 is an apocalyptic number.

It is an amenable number.

639372869 is a deficient number, since it is larger than the sum of its proper divisors (1).

639372869 is an equidigital number, since it uses as much as digits as its factorization.

639372869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2939328, while the sum is 53.

The square root of 639372869 is about 25285.8234787796. The cubic root of 639372869 is about 861.4923021926.

The spelling of 639372869 in words is "six hundred thirty-nine million, three hundred seventy-two thousand, eight hundred sixty-nine".