21388394496 has 136 divisors (see below), whose sum is σ = 65187375424. Its totient is φ = 6110576640.

The previous prime is 21388394491. The next prime is 21388394507. The reversal of 21388394496 is 69449388312.

It is not an unprimeable number, because it can be changed into a prime (21388394491) 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, 1368486 + ... + 1384026.

Almost surely, 2^21388394496 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 21388394496, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32593687712).

21388394496 is an abundant number, since it is smaller than the sum of its proper divisors (43798980928).

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

21388394496 is an frugal number, since it uses more digits than its factorization.

21388394496 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15583 (or 15553 counting only the distinct ones).

The product of its digits is 8957952, while the sum is 57.

The spelling of 21388394496 in words is "twenty-one billion, three hundred eighty-eight million, three hundred ninety-four thousand, four hundred ninety-six".