21691966604261 has 16 divisors (see below), whose sum is σ = 21986498476800. Its totient is φ = 21399184741248.

The previous prime is 21691966604179. The next prime is 21691966604291. The reversal of 21691966604261 is 16240666919612.

It is a cyclic number.

It is not a de Polignac number, because 21691966604261 - 2²⁶ = 21691899495397 is a prime.

It is a super-2 number, since 2×21691966604261² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21691966604261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691966604291) 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, 552796880 + ... + 552836118.

It is an arithmetic number, because the mean of its divisors is an integer number (1374156154800).

Almost surely, 2^{21691966604261} is an apocalyptic number.

It is an amenable number.

21691966604261 is a deficient number, since it is larger than the sum of its proper divisors (294531872539).

21691966604261 is a wasteful number, since it uses less digits than its factorization.

21691966604261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61348.

The product of its (nonzero) digits is 10077696, while the sum is 59.

The spelling of 21691966604261 in words is "twenty-one trillion, six hundred ninety-one billion, nine hundred sixty-six million, six hundred four thousand, two hundred sixty-one".