639781345 has 16 divisors (see below), whose sum is σ = 881256960. Its totient is φ = 436785984.

The previous prime is 639781339. The next prime is 639781361. The reversal of 639781345 is 543187936.

It is a cyclic number.

It is not a de Polignac number, because 639781345 - 2⁵ = 639781313 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639781295 and 639781304.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31897 + ... + 47926.

It is an arithmetic number, because the mean of its divisors is an integer number (55078560).

Almost surely, 2^639781345 is an apocalyptic number.

It is an amenable number.

639781345 is a deficient number, since it is larger than the sum of its proper divisors (241475615).

639781345 is a wasteful number, since it uses less digits than its factorization.

639781345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80064.

The product of its digits is 544320, while the sum is 46.

The square root of 639781345 is about 25293.8993632852. The cubic root of 639781345 is about 861.6757236013.

The spelling of 639781345 in words is "six hundred thirty-nine million, seven hundred eighty-one thousand, three hundred forty-five".