21646751896449 has 27 divisors (see below), whose sum is σ = 31322242979209. Its totient is φ = 14405960106240.

The previous prime is 21646751896421. The next prime is 21646751896463. The reversal of 21646751896449 is 94469815764612.

The square root of 21646751896449 is 4652607.

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

21646751896449 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 6 + 7 + 518 + 9 + 64 + 49 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1365960200049 + 20280791696400 = 1168743^2 + 4503420^2 .

It is not a de Polignac number, because 21646751896449 - 2¹³ = 21646751888257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21646751896499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11459370097 + ... + 11459371985.

Almost surely, 2^{21646751896449} is an apocalyptic number.

21646751896449 is the 4652607-th square number.

21646751896449 is the 2326304-th centered octagonal number.

It is an amenable number.

21646751896449 is a deficient number, since it is larger than the sum of its proper divisors (9675491082760).

21646751896449 is an frugal number, since it uses more digits than its factorization.

21646751896449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5426 (or 2713 counting only the distinct ones).

The product of its digits is 627056640, while the sum is 72.

The spelling of 21646751896449 in words is "twenty-one trillion, six hundred forty-six billion, seven hundred fifty-one million, eight hundred ninety-six thousand, four hundred forty-nine".