21705237396544 has 63 divisors (see below), whose sum is σ = 46640410818687. Its totient is φ = 10017578248704.

The previous prime is 21705237396529. The next prime is 21705237396569. The reversal of 21705237396544 is 44569373250712.

The square root of 21705237396544 is 4658888.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 6922750356544 + 14782487040000 = 2631112^2 + 3844800^2 .

It is a super-2 number, since 2×21705237396544² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 484501954 + ... + 484546750.

It is an arithmetic number, because the mean of its divisors is an integer number (740323981249).

Almost surely, 2^{21705237396544} is an apocalyptic number.

21705237396544 is the 4658888-th square number.

It is an amenable number.

21705237396544 is an abundant number, since it is smaller than the sum of its proper divisors (24935173422143).

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

21705237396544 is an frugal number, since it uses more digits than its factorization.

21705237396544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89632 (or 44812 counting only the distinct ones).

The product of its (nonzero) digits is 38102400, while the sum is 58.

The spelling of 21705237396544 in words is "twenty-one trillion, seven hundred five billion, two hundred thirty-seven million, three hundred ninety-six thousand, five hundred forty-four".