640072621 has 8 divisors (see below), whose sum is σ = 645515360. Its totient is φ = 634642128.

The previous prime is 640072619. The next prime is 640072691. The reversal of 640072621 is 126270046.

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 640072621 - 2¹ = 640072619 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 640072621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640072691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123535 + ... + 128611.

It is an arithmetic number, because the mean of its divisors is an integer number (80689420).

Almost surely, 2^640072621 is an apocalyptic number.

It is an amenable number.

640072621 is a deficient number, since it is larger than the sum of its proper divisors (5442739).

640072621 is a wasteful number, since it uses less digits than its factorization.

640072621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6123.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 640072621 is about 25299.6565391706. The cubic root of 640072621 is about 861.8064700303.

The spelling of 640072621 in words is "six hundred forty million, seventy-two thousand, six hundred twenty-one".