81358511 has 4 divisors (see below), whose sum is σ = 87616872. Its totient is φ = 75100152.

The previous prime is 81358493. The next prime is 81358517. The reversal of 81358511 is 11585318.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81358511 - 2²⁶ = 14249647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81358517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3129161 + ... + 3129186.

It is an arithmetic number, because the mean of its divisors is an integer number (21904218).

Almost surely, 2^81358511 is an apocalyptic number.

81358511 is a deficient number, since it is larger than the sum of its proper divisors (6258361).

81358511 is a wasteful number, since it uses less digits than its factorization.

81358511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6258360.

The product of its digits is 4800, while the sum is 32.

The square root of 81358511 is about 9019.8952876405. The cubic root of 81358511 is about 433.3122801737.

The spelling of 81358511 in words is "eighty-one million, three hundred fifty-eight thousand, five hundred eleven".