81126567421 has 2 divisors, whose sum is σ = 81126567422. Its totient is φ = 81126567420.

The previous prime is 81126567397. The next prime is 81126567427. The reversal of 81126567421 is 12476562118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65247039225 + 15879528196 = 255435^2 + 126014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81126567421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81126567427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40563283710 + 40563283711.

It is an arithmetic number, because the mean of its divisors is an integer number (40563283711).

Almost surely, 2^81126567421 is an apocalyptic number.

It is an amenable number.

81126567421 is a deficient number, since it is larger than the sum of its proper divisors (1).

81126567421 is an equidigital number, since it uses as much as digits as its factorization.

81126567421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 161280, while the sum is 43.

The spelling of 81126567421 in words is "eighty-one billion, one hundred twenty-six million, five hundred sixty-seven thousand, four hundred twenty-one".