81493879 has 2 divisors, whose sum is σ = 81493880. Its totient is φ = 81493878.

The previous prime is 81493877. The next prime is 81493891. The reversal of 81493879 is 97839418.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81493879 - 2¹ = 81493877 is a prime.

Together with 81493877, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81493873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40746939 + 40746940.

It is an arithmetic number, because the mean of its divisors is an integer number (40746940).

Almost surely, 2^81493879 is an apocalyptic number.

81493879 is a deficient number, since it is larger than the sum of its proper divisors (1).

81493879 is an equidigital number, since it uses as much as digits as its factorization.

81493879 is an evil number, because the sum of its binary digits is even.

The product of its digits is 435456, while the sum is 49.

The square root of 81493879 is about 9027.3960254328. The cubic root of 81493879 is about 433.5524685868.

The spelling of 81493879 in words is "eighty-one million, four hundred ninety-three thousand, eight hundred seventy-nine".