21261523264205 has 24 divisors (see below), whose sum is σ = 29689947784440. Its totient is φ = 14574124723200.

The previous prime is 21261523264187. The next prime is 21261523264259. The reversal of 21261523264205 is 50246232516212.

It can be written as a sum of positive squares in 4 ways, for example, as 58021729129 + 21203501535076 = 240877^2 + 4604726^2 .

It is not a de Polignac number, because 21261523264205 - 2²⁰ = 21261522215629 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14804960 + ... + 16177449.

It is an arithmetic number, because the mean of its divisors is an integer number (1237081157685).

Almost surely, 2^{21261523264205} is an apocalyptic number.

It is an amenable number.

21261523264205 is a deficient number, since it is larger than the sum of its proper divisors (8428424520235).

21261523264205 is a wasteful number, since it uses less digits than its factorization.

21261523264205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30985229 (or 30985222 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 41.

The spelling of 21261523264205 in words is "twenty-one trillion, two hundred sixty-one billion, five hundred twenty-three million, two hundred sixty-four thousand, two hundred five".