21971084640 has 96 divisors (see below), whose sum is σ = 69234600960. Its totient is φ = 5856781824.

The previous prime is 21971084621. The next prime is 21971084647. The reversal of 21971084640 is 4648017912.

It is a tau number, because it is divible by the number of its divisors (96).

It is a junction number, because it is equal to n+sod(n) for n = 21971084592 and 21971084601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21971084647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1605507 + ... + 1619133.

It is an arithmetic number, because the mean of its divisors is an integer number (721193760).

Almost surely, 2^21971084640 is an apocalyptic number.

21971084640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21971084640 is an abundant number, since it is smaller than the sum of its proper divisors (47263516320).

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

21971084640 is a wasteful number, since it uses less digits than its factorization.

21971084640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17004 (or 16996 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 42.

The spelling of 21971084640 in words is "twenty-one billion, nine hundred seventy-one million, eighty-four thousand, six hundred forty".