639779827 has 2 divisors, whose sum is σ = 639779828. Its totient is φ = 639779826.

The previous prime is 639779797. The next prime is 639779863. The reversal of 639779827 is 728977936.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639779827 is a prime.

It is a super-2 number, since 2×639779827² = 818636454072299858, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (639779927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319889913 + 319889914.

It is an arithmetic number, because the mean of its divisors is an integer number (319889914).

Almost surely, 2^639779827 is an apocalyptic number.

639779827 is a deficient number, since it is larger than the sum of its proper divisors (1).

639779827 is an equidigital number, since it uses as much as digits as its factorization.

639779827 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8001504, while the sum is 58.

The square root of 639779827 is about 25293.8693560317. The cubic root of 639779827 is about 861.6750421056.

The spelling of 639779827 in words is "six hundred thirty-nine million, seven hundred seventy-nine thousand, eight hundred twenty-seven".