639967420 has 12 divisors (see below), whose sum is σ = 1343931624. Its totient is φ = 255986960.

The previous prime is 639967373. The next prime is 639967459. The reversal of 639967420 is 24769936.

It is a super-2 number, since 2×639967420² = 819116597322912800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15999166 + ... + 15999205.

It is an arithmetic number, because the mean of its divisors is an integer number (111994302).

Almost surely, 2^639967420 is an apocalyptic number.

It is an amenable number.

639967420 is an abundant number, since it is smaller than the sum of its proper divisors (703964204).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639967420 is a wasteful number, since it uses less digits than its factorization.

639967420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31998380 (or 31998378 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 46.

The square root of 639967420 is about 25297.5773543634. The cubic root of 639967420 is about 861.7592525392.

The spelling of 639967420 in words is "six hundred thirty-nine million, nine hundred sixty-seven thousand, four hundred twenty".