21125999944 has 48 divisors (see below), whose sum is σ = 46766188080. Its totient is φ = 8918854560.

The previous prime is 21125999941. The next prime is 21125999957. The reversal of 21125999944 is 44999952112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21125999941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 375922 + ... + 428449.

It is an arithmetic number, because the mean of its divisors is an integer number (974295585).

Almost surely, 2^21125999944 is an apocalyptic number.

It is an amenable number.

21125999944 is an abundant number, since it is smaller than the sum of its proper divisors (25640188136).

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

21125999944 is a wasteful number, since it uses less digits than its factorization.

21125999944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804458 (or 804447 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 55.

The spelling of 21125999944 in words is "twenty-one billion, one hundred twenty-five million, nine hundred ninety-nine thousand, nine hundred forty-four".