21989257920 has 560 divisors, whose sum is σ = 94665637440. Its totient is φ = 4729798656.

The previous prime is 21989257919. The next prime is 21989257951. The reversal of 21989257920 is 2975298912.

It is a tau number, because it is divible by the number of its divisors (560).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 3080916 + ... + 3088044.

Almost surely, 2^21989257920 is an apocalyptic number.

21989257920 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 21989257920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47332818720).

21989257920 is an abundant number, since it is smaller than the sum of its proper divisors (72676379520).

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

21989257920 is a wasteful number, since it uses less digits than its factorization.

21989257920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7182 (or 7163 counting only the distinct ones).

The product of its (nonzero) digits is 1632960, while the sum is 54.

The spelling of 21989257920 in words is "twenty-one billion, nine hundred eighty-nine million, two hundred fifty-seven thousand, nine hundred twenty".