21247911944 has 96 divisors (see below), whose sum is σ = 46897420320. Its totient is φ = 8998262784.

The previous prime is 21247911943. The next prime is 21247912031. The reversal of 21247911944 is 44911974212.

It is a junction number, because it is equal to n+sod(n) for n = 21247911895 and 21247911904.

It is not an unprimeable number, because it can be changed into a prime (21247911943) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12331067 + ... + 12332789.

It is an arithmetic number, because the mean of its divisors is an integer number (488514795).

Almost surely, 2^21247911944 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21247911944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23448710160).

21247911944 is an abundant number, since it is smaller than the sum of its proper divisors (25649508376).

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

21247911944 is a wasteful number, since it uses less digits than its factorization.

21247911944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2099 (or 2088 counting only the distinct ones).

The product of its digits is 145152, while the sum is 44.

The spelling of 21247911944 in words is "twenty-one billion, two hundred forty-seven million, nine hundred eleven thousand, nine hundred forty-four".