21309471888 has 120 divisors (see below), whose sum is σ = 58209899328. Its totient is φ = 6716507904.

The previous prime is 21309471877. The next prime is 21309471923. The reversal of 21309471888 is 88817490312.

It is a hoax number, since the sum of its digits (51) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21309471888.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13809645 + ... + 13811187.

Almost surely, 2^21309471888 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 21309471888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29104949664).

21309471888 is an abundant number, since it is smaller than the sum of its proper divisors (36900427440).

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

21309471888 is a wasteful number, since it uses less digits than its factorization.

21309471888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2389 (or 2364 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 51.

The spelling of 21309471888 in words is "twenty-one billion, three hundred nine million, four hundred seventy-one thousand, eight hundred eighty-eight".