639620 has 12 divisors (see below), whose sum is σ = 1343244. Its totient is φ = 255840.

The previous prime is 639601. The next prime is 639631. The reversal of 639620 is 26936.

It can be written as a sum of positive squares in 2 ways, for example, as 118336 + 521284 = 344^2 + 722^2 .

It is a super-2 number, since 2×639620² = 818227488800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 639620.

It is an unprimeable number.

639620 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15971 + ... + 16010.

It is an arithmetic number, because the mean of its divisors is an integer number (111937).

2⁶³⁹⁶²⁰ is an apocalyptic number.

It is an amenable number.

639620 is an abundant number, since it is smaller than the sum of its proper divisors (703624).

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

639620 is a wasteful number, since it uses less digits than its factorization.

639620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31990 (or 31988 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 639620 is about 799.7624647356. The cubic root of 639620 is about 86.1603282832.

The spelling of 639620 in words is "six hundred thirty-nine thousand, six hundred twenty".