21115664472 has 128 divisors (see below), whose sum is σ = 61921728000. Its totient is φ = 5997769344.

The previous prime is 21115664461. The next prime is 21115664483. The reversal of 21115664472 is 27446651112.

It is an interprime number because it is at equal distance from previous prime (21115664461) and next prime (21115664483).

It is a self number, because there is not a number n which added to its sum of digits gives 21115664472.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1416723 + ... + 1431549.

It is an arithmetic number, because the mean of its divisors is an integer number (483763500).

Almost surely, 2^21115664472 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 21115664472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30960864000).

21115664472 is an abundant number, since it is smaller than the sum of its proper divisors (40806063528).

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

21115664472 is a wasteful number, since it uses less digits than its factorization.

21115664472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15030 (or 15012 counting only the distinct ones).

The product of its digits is 80640, while the sum is 39.

The spelling of 21115664472 in words is "twenty-one billion, one hundred fifteen million, six hundred sixty-four thousand, four hundred seventy-two".