639001621 has 8 divisors (see below), whose sum is σ = 641725784. Its totient is φ = 636284160.

The previous prime is 639001607. The next prime is 639001651. The reversal of 639001621 is 126100936.

It can be written as a sum of positive squares in 4 ways, for example, as 50211396 + 588790225 = 7086^2 + 24265^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 639001621 - 2²³ = 630613013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 639001621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639001651) 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, 279001 + ... + 281281.

It is an arithmetic number, because the mean of its divisors is an integer number (80215723).

Almost surely, 2^639001621 is an apocalyptic number.

It is an amenable number.

639001621 is a deficient number, since it is larger than the sum of its proper divisors (2724163).

639001621 is a wasteful number, since it uses less digits than its factorization.

639001621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3351.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 639001621 is about 25278.4813823932. The cubic root of 639001621 is about 861.3255298069.

The spelling of 639001621 in words is "six hundred thirty-nine million, one thousand, six hundred twenty-one".