639680437 has 8 divisors (see below), whose sum is σ = 738882432. Its totient is φ = 547320000.

The previous prime is 639680411. The next prime is 639680449. The reversal of 639680437 is 734086936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639680437 is a prime.

It is a super-2 number, since 2×639680437² = 818382122961021938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639680477) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1710189 + ... + 1710562.

It is an arithmetic number, because the mean of its divisors is an integer number (92360304).

Almost surely, 2^639680437 is an apocalyptic number.

It is an amenable number.

639680437 is a deficient number, since it is larger than the sum of its proper divisors (99201995).

639680437 is a wasteful number, since it uses less digits than its factorization.

639680437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3420779.

The product of its (nonzero) digits is 653184, while the sum is 46.

The square root of 639680437 is about 25291.9045743890. The cubic root of 639680437 is about 861.6304192973.

The spelling of 639680437 in words is "six hundred thirty-nine million, six hundred eighty thousand, four hundred thirty-seven".