81290879 has 2 divisors, whose sum is σ = 81290880. Its totient is φ = 81290878.

The previous prime is 81290861. The next prime is 81290893. The reversal of 81290879 is 97809218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81290879 - 2⁸ = 81290623 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81290819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40645439 + 40645440.

It is an arithmetic number, because the mean of its divisors is an integer number (40645440).

Almost surely, 2^81290879 is an apocalyptic number.

81290879 is a deficient number, since it is larger than the sum of its proper divisors (1).

81290879 is an equidigital number, since it uses as much as digits as its factorization.

81290879 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 81290879 is about 9016.1454624468. The cubic root of 81290879 is about 433.1921784167.

The spelling of 81290879 in words is "eighty-one million, two hundred ninety thousand, eight hundred seventy-nine".