21489697920 has 256 divisors, whose sum is σ = 70339363200. Its totient is φ = 5578653696.

The previous prime is 21489697919. The next prime is 21489697937. The reversal of 21489697920 is 2979698412.

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, 11448022 + ... + 11449898.

Almost surely, 2^21489697920 is an apocalyptic number.

21489697920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21489697920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35169681600).

21489697920 is an abundant number, since it is smaller than the sum of its proper divisors (48849665280).

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

21489697920 is a wasteful number, since it uses less digits than its factorization.

21489697920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2055 (or 2043 counting only the distinct ones).

The product of its (nonzero) digits is 3919104, while the sum is 57.

The spelling of 21489697920 in words is "twenty-one billion, four hundred eighty-nine million, six hundred ninety-seven thousand, nine hundred twenty".