21256686494784 has 224 divisors, whose sum is σ = 67302150384000. Its totient is φ = 6540086458368.

The previous prime is 21256686494783. The next prime is 21256686494807. The reversal of 21256686494784 is 48749468665212.

21256686494784 is a `hidden beast` number, since 2 + 1 + 2 + 5 + 6 + 68 + 6 + 494 + 78 + 4 = 666.

It is a hoax number, since the sum of its digits (72) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is not an unprimeable number, because it can be changed into a prime (21256686494783) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 574812807 + ... + 574849785.

It is an arithmetic number, because the mean of its divisors is an integer number (300456028500).

Almost surely, 2^{21256686494784} is an apocalyptic number.

21256686494784 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 21256686494784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33651075192000).

21256686494784 is an abundant number, since it is smaller than the sum of its proper divisors (46045463889216).

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

21256686494784 is a wasteful number, since it uses less digits than its factorization.

21256686494784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62602 (or 62586 counting only the distinct ones).

The product of its digits is 1114767360, while the sum is 72.

The spelling of 21256686494784 in words is "twenty-one trillion, two hundred fifty-six billion, six hundred eighty-six million, four hundred ninety-four thousand, seven hundred eighty-four".