81387479 has 2 divisors, whose sum is σ = 81387480. Its totient is φ = 81387478.

The previous prime is 81387473. The next prime is 81387487. The reversal of 81387479 is 97478318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81387479 - 2⁸ = 81387223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81387473) 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, 40693739 + 40693740.

It is an arithmetic number, because the mean of its divisors is an integer number (40693740).

Almost surely, 2^81387479 is an apocalyptic number.

81387479 is a deficient number, since it is larger than the sum of its proper divisors (1).

81387479 is an equidigital number, since it uses as much as digits as its factorization.

81387479 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 47.

The square root of 81387479 is about 9021.5009283378. The cubic root of 81387479 is about 433.3637015535.

The spelling of 81387479 in words is "eighty-one million, three hundred eighty-seven thousand, four hundred seventy-nine".