21255616145461 has 2 divisors, whose sum is σ = 21255616145462. Its totient is φ = 21255616145460.

The previous prime is 21255616145299. The next prime is 21255616145497. The reversal of 21255616145461 is 16454161655212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19076541228900 + 2179074916561 = 4367670^2 + 1476169^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255616145461 - 2¹⁹ = 21255615621173 is a prime.

It is a super-2 number, since 2×21255616145461² (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 (21255616146461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627808072730 + 10627808072731.

It is an arithmetic number, because the mean of its divisors is an integer number (10627808072731).

Almost surely, 2^{21255616145461} is an apocalyptic number.

It is an amenable number.

21255616145461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255616145461 is an equidigital number, since it uses as much as digits as its factorization.

21255616145461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728000, while the sum is 49.

The spelling of 21255616145461 in words is "twenty-one trillion, two hundred fifty-five billion, six hundred sixteen million, one hundred forty-five thousand, four hundred sixty-one".