21805336169 has 4 divisors (see below), whose sum is σ = 21821844180. Its totient is φ = 21788828160.

The previous prime is 21805336121. The next prime is 21805336177. The reversal of 21805336169 is 96163350812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8583096025 + 13222240144 = 92645^2 + 114988^2 .

It is a cyclic number.

It is not a de Polignac number, because 21805336169 - 2⁸ = 21805335913 is a prime.

It is a super-2 number, since 2×21805336169² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21805336199) 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, 8252024 + ... + 8254665.

It is an arithmetic number, because the mean of its divisors is an integer number (5455461045).

Almost surely, 2^21805336169 is an apocalyptic number.

It is an amenable number.

21805336169 is a deficient number, since it is larger than the sum of its proper divisors (16508011).

21805336169 is a wasteful number, since it uses less digits than its factorization.

21805336169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16508010.

The product of its (nonzero) digits is 233280, while the sum is 44.

The spelling of 21805336169 in words is "twenty-one billion, eight hundred five million, three hundred thirty-six thousand, one hundred sixty-nine".