644965902421 has 8 divisors (see below), whose sum is σ = 665807053824. Its totient is φ = 624126988560.

The previous prime is 644965902397. The next prime is 644965902431. The reversal of 644965902421 is 124209569446.

644965902421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644965902421 - 2²³ = 644957513813 is a prime.

It is a super-2 number, since 2×644965902421² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644965902431) 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, 36516 + ... + 1136338.

It is an arithmetic number, because the mean of its divisors is an integer number (83225881728).

Almost surely, 2^644965902421 is an apocalyptic number.

It is an amenable number.

644965902421 is a deficient number, since it is larger than the sum of its proper divisors (20841151403).

644965902421 is a wasteful number, since it uses less digits than its factorization.

644965902421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1118771.

The product of its (nonzero) digits is 3732480, while the sum is 52.

The spelling of 644965902421 in words is "six hundred forty-four billion, nine hundred sixty-five million, nine hundred two thousand, four hundred twenty-one".