21665691432 has 1152 divisors, whose sum is σ = 86046105600. Its totient is φ = 5029516800.

The previous prime is 21665691407. The next prime is 21665691499. The reversal of 21665691432 is 23419656612.

21665691432 is a `hidden beast` number, since 2 + 166 + 56 + 9 + 1 + 432 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 698893257 + ... + 698893287.

It is an arithmetic number, because the mean of its divisors is an integer number (74692800).

Almost surely, 2^21665691432 is an apocalyptic number.

21665691432 is a gapful number since it is divisible by the number (22) 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 21665691432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43023052800).

21665691432 is an abundant number, since it is smaller than the sum of its proper divisors (64380414168).

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

21665691432 is a wasteful number, since it uses less digits than its factorization.

21665691432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 106 counting only the distinct ones).

The product of its digits is 466560, while the sum is 45.

The spelling of 21665691432 in words is "twenty-one billion, six hundred sixty-five million, six hundred ninety-one thousand, four hundred thirty-two".