21638410804261 has 4 divisors (see below), whose sum is σ = 21639609028800. Its totient is φ = 21637212579724.

The previous prime is 21638410804237. The next prime is 21638410804267. The reversal of 21638410804261 is 16240801483612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21638410804261 - 2⁷ = 21638410804133 is a prime.

It is a super-2 number, since 2×21638410804261² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21638410804267) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 599085181 + ... + 599121298.

It is an arithmetic number, because the mean of its divisors is an integer number (5409902257200).

Almost surely, 2^{21638410804261} is an apocalyptic number.

It is an amenable number.

21638410804261 is a deficient number, since it is larger than the sum of its proper divisors (1198224539).

21638410804261 is a wasteful number, since it uses less digits than its factorization.

21638410804261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1198224538.

The product of its (nonzero) digits is 442368, while the sum is 46.

The spelling of 21638410804261 in words is "twenty-one trillion, six hundred thirty-eight billion, four hundred ten million, eight hundred four thousand, two hundred sixty-one".