21668131249216 has 21 divisors (see below), whose sum is σ = 42997771844391. Its totient is φ = 10834047004992.

The previous prime is 21668131249201. The next prime is 21668131249217. The reversal of 21668131249216 is 61294213186612.

The square root of 21668131249216 is 4654904.

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

It is a super-2 number, since 2×21668131249216² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21668131249217) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 36948301 + ... + 37530163.

It is an arithmetic number, because the mean of its divisors is an integer number (2047512944971).

Almost surely, 2^{21668131249216} is an apocalyptic number.

21668131249216 is the 4654904-th square number.

It is an amenable number.

21668131249216 is a deficient number, since it is larger than the sum of its proper divisors (21329640595175).

21668131249216 is an frugal number, since it uses more digits than its factorization.

21668131249216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1163738 (or 581865 counting only the distinct ones).

The product of its digits is 1492992, while the sum is 52.

The spelling of 21668131249216 in words is "twenty-one trillion, six hundred sixty-eight billion, one hundred thirty-one million, two hundred forty-nine thousand, two hundred sixteen".