81414815 has 4 divisors (see below), whose sum is σ = 97697784. Its totient is φ = 65131848.

The previous prime is 81414811. The next prime is 81414833. The reversal of 81414815 is 51841418.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51841418 = 2 ⋅25920709.

It is a cyclic number.

It is not a de Polignac number, because 81414815 - 2² = 81414811 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 (81414811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8141477 + ... + 8141486.

It is an arithmetic number, because the mean of its divisors is an integer number (24424446).

Almost surely, 2^81414815 is an apocalyptic number.

81414815 is a deficient number, since it is larger than the sum of its proper divisors (16282969).

81414815 is a wasteful number, since it uses less digits than its factorization.

81414815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16282968.

The product of its digits is 5120, while the sum is 32.

The square root of 81414815 is about 9023.0158483735. The cubic root of 81414815 is about 433.4122147656.

The spelling of 81414815 in words is "eighty-one million, four hundred fourteen thousand, eight hundred fifteen".