21536317440 has 672 divisors, whose sum is σ = 83910318336. Its totient is φ = 5064622080.

The previous prime is 21536317409. The next prime is 21536317459. The reversal of 21536317440 is 4471363512.

21536317440 is a `hidden beast` number, since 2 + 15 + 3 + 631 + 7 + 4 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21536317395 and 21536317404.

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, 190586824 + ... + 190586936.

Almost surely, 2^21536317440 is an apocalyptic number.

21536317440 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 21536317440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41955159168).

21536317440 is an abundant number, since it is smaller than the sum of its proper divisors (62374000896).

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

21536317440 is a wasteful number, since it uses less digits than its factorization.

21536317440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208 (or 181 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21536317440 in words is "twenty-one billion, five hundred thirty-six million, three hundred seventeen thousand, four hundred forty".