21688902144 has 600 divisors, whose sum is σ = 81196201548. Its totient is φ = 5713182720.

The previous prime is 21688902101. The next prime is 21688902187. The reversal of 21688902144 is 44120988612.

It is an interprime number because it is at equal distance from previous prime (21688902101) and next prime (21688902187).

It can be written as a sum of positive squares in 2 ways, for example, as 19631372544 + 2057529600 = 140112^2 + 45360^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21688902144.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 26417254 + ... + 26418074.

Almost surely, 2^21688902144 is an apocalyptic number.

21688902144 is a gapful number since it is divisible by the number (24) 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 21688902144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40598100774).

21688902144 is an abundant number, since it is smaller than the sum of its proper divisors (59507299404).

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

21688902144 is an equidigital number, since it uses as much as digits as its factorization.

21688902144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878 (or 846 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 21688902144 in words is "twenty-one billion, six hundred eighty-eight million, nine hundred two thousand, one hundred forty-four".