21531949286400 has 1056 divisors, whose sum is σ = 91484565922560. Its totient is φ = 4921498828800.

The previous prime is 21531949286387. The next prime is 21531949286447. The reversal of 21531949286400 is 468294913512.

It is a happy number.

21531949286400 is a `hidden beast` number, since 2 + 1 + 5 + 31 + 9 + 492 + 86 + 40 + 0 = 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 polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 391882930 + ... + 391937870.

Almost surely, 2^{21531949286400} is an apocalyptic number.

21531949286400 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 21531949286400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45742282961280).

21531949286400 is an abundant number, since it is smaller than the sum of its proper divisors (69952616636160).

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

21531949286400 is an frugal number, since it uses more digits than its factorization.

21531949286400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54999 (or 54958 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 54.

The spelling of 21531949286400 in words is "twenty-one trillion, five hundred thirty-one billion, nine hundred forty-nine million, two hundred eighty-six thousand, four hundred".