21621210542116 has 6 divisors (see below), whose sum is σ = 37837118448710. Its totient is φ = 10810605271056.

The previous prime is 21621210542089. The next prime is 21621210542137. The reversal of 21621210542116 is 61124501212612.

It can be written as a sum of positive squares in only one way, i.e., 14643709424100 + 6977501118016 = 3826710^2 + 2641496^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2702651317761 + ... + 2702651317768.

Almost surely, 2^{21621210542116} is an apocalyptic number.

It is an amenable number.

21621210542116 is a deficient number, since it is larger than the sum of its proper divisors (16215907906594).

21621210542116 is a wasteful number, since it uses less digits than its factorization.

21621210542116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5405302635533 (or 5405302635531 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 34.

Adding to 21621210542116 its reverse (61124501212612), we get a palindrome (82745711754728).

The spelling of 21621210542116 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred ten million, five hundred forty-two thousand, one hundred sixteen".