21687989440 has 224 divisors, whose sum is σ = 57057243264. Its totient is φ = 7803371520.

The previous prime is 21687989431. The next prime is 21687989441. The reversal of 21687989440 is 4498978612.

It is not an unprimeable number, because it can be changed into a prime (21687989441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28649542 + ... + 28650298.

It is an arithmetic number, because the mean of its divisors is an integer number (254719836).

Almost surely, 2^21687989440 is an apocalyptic number.

21687989440 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 21687989440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28528621632).

21687989440 is an abundant number, since it is smaller than the sum of its proper divisors (35369253824).

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

21687989440 is a wasteful number, since it uses less digits than its factorization.

21687989440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 955 (or 945 counting only the distinct ones).

The product of its (nonzero) digits is 6967296, while the sum is 58.

The spelling of 21687989440 in words is "twenty-one billion, six hundred eighty-seven million, nine hundred eighty-nine thousand, four hundred forty".