21621404666633 has 16 divisors (see below), whose sum is σ = 21726690507600. Its totient is φ = 21516333834240.

The previous prime is 21621404666599. The next prime is 21621404666647. The reversal of 21621404666633 is 33666640412612.

It can be written as a sum of positive squares in 8 ways, for example, as 700038442489 + 20921366224144 = 836683^2 + 4573988^2 .

It is not a de Polignac number, because 21621404666633 - 2⁴² = 17223358155529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21621404666333) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1068610685 + ... + 1068630917.

It is an arithmetic number, because the mean of its divisors is an integer number (1357918156725).

Almost surely, 2^{21621404666633} is an apocalyptic number.

It is an amenable number.

21621404666633 is a deficient number, since it is larger than the sum of its proper divisors (105285840967).

21621404666633 is a wasteful number, since it uses less digits than its factorization.

21621404666633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25292.

The product of its (nonzero) digits is 4478976, while the sum is 50.

The spelling of 21621404666633 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred four million, six hundred sixty-six thousand, six hundred thirty-three".