644002992 has 60 divisors (see below), whose sum is σ = 1804069800. Its totient is φ = 214458624.

The previous prime is 644002991. The next prime is 644003011. The reversal of 644002992 is 299200446.

644002992 is a `hidden beast` number, since 644 + 0 + 0 + 2 + 9 + 9 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (644002991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 237259 + ... + 239957.

It is an arithmetic number, because the mean of its divisors is an integer number (30067830).

Almost surely, 2^644002992 is an apocalyptic number.

It is an amenable number.

644002992 is an abundant number, since it is smaller than the sum of its proper divisors (1160066808).

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

644002992 is a wasteful number, since it uses less digits than its factorization.

644002992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4370 (or 4361 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 644002992 is about 25377.2140314890. The cubic root of 644002992 is about 863.5668482122.

The spelling of 644002992 in words is "six hundred forty-four million, two thousand, nine hundred ninety-two".