664637628 has 24 divisors (see below), whose sum is σ = 1559790288. Its totient is φ = 220264576.

The previous prime is 664637621. The next prime is 664637641. The reversal of 664637628 is 826736466.

It is a super-4 number, since 4×664637628⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664637621) 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, 158001 + ... + 162152.

It is an arithmetic number, because the mean of its divisors is an integer number (64991262).

Almost surely, 2^664637628 is an apocalyptic number.

It is an amenable number.

664637628 is an abundant number, since it is smaller than the sum of its proper divisors (895152660).

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

664637628 is a wasteful number, since it uses less digits than its factorization.

664637628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320333 (or 320331 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 48.

The square root of 664637628 is about 25780.5668673131. The cubic root of 664637628 is about 872.6932998100.

The spelling of 664637628 in words is "six hundred sixty-four million, six hundred thirty-seven thousand, six hundred twenty-eight".