21705645798144 has 324 divisors, whose sum is σ = 78616326389328. Its totient is φ = 5637829570560.

The previous prime is 21705645798107. The next prime is 21705645798181. The reversal of 21705645798144 is 44189754650712.

It is a happy number.

21705645798144 is a `hidden beast` number, since 2 + 1 + 7 + 0 + 56 + 4 + 579 + 8 + 1 + 4 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (21705645798107) and next prime (21705645798181).

It is a super-2 number, since 2×21705645798144² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3609819 + ... + 7512794.

Almost surely, 2^{21705645798144} is an apocalyptic number.

21705645798144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21705645798144 is an abundant number, since it is smaller than the sum of its proper divisors (56910680591184).

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

21705645798144 is a wasteful number, since it uses less digits than its factorization.

21705645798144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11122664 (or 11122636 counting only the distinct ones).

The product of its (nonzero) digits is 67737600, while the sum is 63.

The spelling of 21705645798144 in words is "twenty-one trillion, seven hundred five billion, six hundred forty-five million, seven hundred ninety-eight thousand, one hundred forty-four".