21725165424397 has 2 divisors, whose sum is σ = 21725165424398. Its totient is φ = 21725165424396.

The previous prime is 21725165424317. The next prime is 21725165424421. The reversal of 21725165424397 is 79342456152712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19090861137481 + 2634304286916 = 4369309^2 + 1623054^2 .

It is a cyclic number.

It is not a de Polignac number, because 21725165424397 - 2⁷ = 21725165424269 is a prime.

It is a super-2 number, since 2×21725165424397² (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 (21725165424317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10862582712198 + 10862582712199.

It is an arithmetic number, because the mean of its divisors is an integer number (10862582712199).

Almost surely, 2^{21725165424397} is an apocalyptic number.

It is an amenable number.

21725165424397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21725165424397 is an equidigital number, since it uses as much as digits as its factorization.

21725165424397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25401600, while the sum is 58.

The spelling of 21725165424397 in words is "twenty-one trillion, seven hundred twenty-five billion, one hundred sixty-five million, four hundred twenty-four thousand, three hundred ninety-seven".