21365025473221 has 2 divisors, whose sum is σ = 21365025473222. Its totient is φ = 21365025473220.

The previous prime is 21365025473179. The next prime is 21365025473249. The reversal of 21365025473221 is 12237452056312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20616013116196 + 749012357025 = 4540486^2 + 865455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21365025473221 - 2¹⁹ = 21365024948933 is a prime.

It is a super-2 number, since 2×21365025473221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21365025443221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682512736610 + 10682512736611.

It is an arithmetic number, because the mean of its divisors is an integer number (10682512736611).

Almost surely, 2^{21365025473221} is an apocalyptic number.

It is an amenable number.

21365025473221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365025473221 is an equidigital number, since it uses as much as digits as its factorization.

21365025473221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 604800, while the sum is 43.

The spelling of 21365025473221 in words is "twenty-one trillion, three hundred sixty-five billion, twenty-five million, four hundred seventy-three thousand, two hundred twenty-one".