639880877 has 2 divisors, whose sum is σ = 639880878. Its totient is φ = 639880876.

The previous prime is 639880873. The next prime is 639880949. The reversal of 639880877 is 778088936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 353966596 + 285914281 = 18814^2 + 16909^2 .

It is a cyclic number.

It is not a de Polignac number, because 639880877 - 2² = 639880873 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639880873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319940438 + 319940439.

It is an arithmetic number, because the mean of its divisors is an integer number (319940439).

Almost surely, 2^639880877 is an apocalyptic number.

It is an amenable number.

639880877 is a deficient number, since it is larger than the sum of its proper divisors (1).

639880877 is an equidigital number, since it uses as much as digits as its factorization.

639880877 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4064256, while the sum is 56.

The square root of 639880877 is about 25295.8667967714. The cubic root of 639880877 is about 861.7204054611.

The spelling of 639880877 in words is "six hundred thirty-nine million, eight hundred eighty thousand, eight hundred seventy-seven".