21001312444 has 12 divisors (see below), whose sum is σ = 42002624944. Its totient is φ = 9000562464.

The previous prime is 21001312439. The next prime is 21001312511. The reversal of 21001312444 is 44421310012.

It is a happy number.

21001312444 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375023409 + ... + 375023464.

Almost surely, 2^21001312444 is an apocalyptic number.

It is an amenable number.

21001312444 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21001312444 is a wasteful number, since it uses less digits than its factorization.

21001312444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 750046884 (or 750046882 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

Adding to 21001312444 its reverse (44421310012), we get a palindrome (65422622456).

The spelling of 21001312444 in words is "twenty-one billion, one million, three hundred twelve thousand, four hundred forty-four".