664236820 has 24 divisors (see below), whose sum is σ = 1502197704. Its totient is φ = 245256576.

The previous prime is 664236817. The next prime is 664236829. The reversal of 664236820 is 28632466.

It can be written as a sum of positive squares in 4 ways, for example, as 35832196 + 628404624 = 5986^2 + 25068^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 664236820.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664236829) 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, 1277119 + ... + 1277638.

It is an arithmetic number, because the mean of its divisors is an integer number (62591571).

Almost surely, 2^664236820 is an apocalyptic number.

It is an amenable number.

664236820 is an abundant number, since it is smaller than the sum of its proper divisors (837960884).

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

664236820 is a wasteful number, since it uses less digits than its factorization.

664236820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2554779 (or 2554777 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 37.

The square root of 664236820 is about 25772.7922429837. The cubic root of 664236820 is about 872.5178393903.

The spelling of 664236820 in words is "six hundred sixty-four million, two hundred thirty-six thousand, eight hundred twenty".