21398972416 has 96 divisors (see below), whose sum is σ = 43660300320. Its totient is φ = 10483089408.

The previous prime is 21398972407. The next prime is 21398972417. The reversal of 21398972416 is 61427989312.

It is not an unprimeable number, because it can be changed into a prime (21398972417) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38008551 + ... + 38009113.

It is an arithmetic number, because the mean of its divisors is an integer number (454794795).

Almost surely, 2^21398972416 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 21398972416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21830150160).

21398972416 is an abundant number, since it is smaller than the sum of its proper divisors (22261327904).

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

21398972416 is an equidigital number, since it uses as much as digits as its factorization.

21398972416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 929 (or 909 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 52.

The spelling of 21398972416 in words is "twenty-one billion, three hundred ninety-eight million, nine hundred seventy-two thousand, four hundred sixteen".