21493651968 has 200 divisors, whose sum is σ = 65523788352. Its totient is φ = 7011477504.

The previous prime is 21493651951. The next prime is 21493651987. The reversal of 21493651968 is 86915639412.

21493651968 is a `hidden beast` number, since 2 + 1 + 493 + 65 + 1 + 96 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1943671 + ... + 1954697.

Almost surely, 2^21493651968 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 21493651968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32761894176).

21493651968 is an abundant number, since it is smaller than the sum of its proper divisors (44030136384).

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

21493651968 is an equidigital number, since it uses as much as digits as its factorization.

21493651968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11104 (or 11079 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 54.

The spelling of 21493651968 in words is "twenty-one billion, four hundred ninety-three million, six hundred fifty-one thousand, nine hundred sixty-eight".