639781213 has 16 divisors (see below), whose sum is σ = 689751936. Its totient is φ = 591252480.

The previous prime is 639781199. The next prime is 639781223. The reversal of 639781213 is 312187936.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639781213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639781223) 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 in 15 ways as a sum of consecutive naturals, for example, 340645 + ... + 342517.

It is an arithmetic number, because the mean of its divisors is an integer number (43109496).

Almost surely, 2^639781213 is an apocalyptic number.

It is an amenable number.

639781213 is a deficient number, since it is larger than the sum of its proper divisors (49970723).

639781213 is a wasteful number, since it uses less digits than its factorization.

639781213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2244.

The product of its digits is 54432, while the sum is 40.

The square root of 639781213 is about 25293.8967539602. The cubic root of 639781213 is about 861.6756643408.

The spelling of 639781213 in words is "six hundred thirty-nine million, seven hundred eighty-one thousand, two hundred thirteen".