644168012 has 12 divisors (see below), whose sum is σ = 1193605560. Its totient is φ = 303137856.

The previous prime is 644168011. The next prime is 644168059. The reversal of 644168012 is 210861446.

It is a self number, because there is not a number n which added to its sum of digits gives 644168012.

It is not an unprimeable number, because it can be changed into a prime (644168011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4736462 + ... + 4736597.

It is an arithmetic number, because the mean of its divisors is an integer number (99467130).

Almost surely, 2^644168012 is an apocalyptic number.

It is an amenable number.

644168012 is a deficient number, since it is larger than the sum of its proper divisors (549437548).

644168012 is a wasteful number, since it uses less digits than its factorization.

644168012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9473080 (or 9473078 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 644168012 is about 25380.4651651620. The cubic root of 644168012 is about 863.6406023370.

The spelling of 644168012 in words is "six hundred forty-four million, one hundred sixty-eight thousand, twelve".