644260022420 has 48 divisors (see below), whose sum is σ = 1546876990848. Its totient is φ = 220795873920.

The previous prime is 644260022411. The next prime is 644260022459. The reversal of 644260022420 is 24220062446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 638507 + ... + 1302386.

It is an arithmetic number, because the mean of its divisors is an integer number (32226603976).

Almost surely, 2^644260022420 is an apocalyptic number.

It is an amenable number.

644260022420 is an abundant number, since it is smaller than the sum of its proper divisors (902616968428).

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

644260022420 is a wasteful number, since it uses less digits than its factorization.

644260022420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1943280 (or 1943278 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 32.

Adding to 644260022420 its reverse (24220062446), we get a palindrome (668480084866).

The spelling of 644260022420 in words is "six hundred forty-four billion, two hundred sixty million, twenty-two thousand, four hundred twenty".