644965902420 has 48 divisors (see below), whose sum is σ = 2063890889088. Its totient is φ = 147420777600.

The previous prime is 644965902397. The next prime is 644965902431. The reversal of 644965902420 is 24209569446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 767816131 + ... + 767816970.

It is an arithmetic number, because the mean of its divisors is an integer number (42997726856).

Almost surely, 2^644965902420 is an apocalyptic number.

644965902420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644965902420 is an abundant number, since it is smaller than the sum of its proper divisors (1418924986668).

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

644965902420 is a wasteful number, since it uses less digits than its factorization.

644965902420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1535633120 (or 1535633118 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 51.

The spelling of 644965902420 in words is "six hundred forty-four billion, nine hundred sixty-five million, nine hundred two thousand, four hundred twenty".