21891599891716 has 9 divisors (see below), whose sum is σ = 38310316186471. Its totient is φ = 10945795267012.

The previous prime is 21891599891713. The next prime is 21891599891737. The reversal of 21891599891716 is 61719899519812.

The square root of 21891599891716 is 4678846.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21891599891713) 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 2 ways as a sum of consecutive naturals, for example, 8187981 + ... + 10527403.

Almost surely, 2^{21891599891716} is an apocalyptic number.

21891599891716 is the 4678846-th square number.

It is an amenable number.

21891599891716 is a deficient number, since it is larger than the sum of its proper divisors (16418716294755).

21891599891716 is an frugal number, since it uses more digits than its factorization.

21891599891716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4678850 (or 2339425 counting only the distinct ones).

The product of its digits is 176359680, while the sum is 76.

The spelling of 21891599891716 in words is "twenty-one trillion, eight hundred ninety-one billion, five hundred ninety-nine million, eight hundred ninety-one thousand, seven hundred sixteen".