21391983504 has 240 divisors, whose sum is σ = 62936400384. Its totient is φ = 6775142400.

The previous prime is 21391983499. The next prime is 21391983521. The reversal of 21391983504 is 40538919312.

It is a happy number.

21391983504 is a `hidden beast` number, since 2 + 139 + 1 + 9 + 8 + 3 + 504 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21391983504.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 91810972 + ... + 91811204.

Almost surely, 2^21391983504 is an apocalyptic number.

21391983504 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 21391983504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31468200192).

21391983504 is an abundant number, since it is smaller than the sum of its proper divisors (41544416880).

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

21391983504 is a wasteful number, since it uses less digits than its factorization.

21391983504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The spelling of 21391983504 in words is "twenty-one billion, three hundred ninety-one million, nine hundred eighty-three thousand, five hundred four".