81415523 has 4 divisors (see below), whose sum is σ = 93046320. Its totient is φ = 69784728.

The previous prime is 81415511. The next prime is 81415531. The reversal of 81415523 is 32551418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32551418 = 2 ⋅16275709.

It is a cyclic number.

It is not a de Polignac number, because 81415523 - 2⁴ = 81415507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81415553) 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, 5815388 + ... + 5815401.

It is an arithmetic number, because the mean of its divisors is an integer number (23261580).

Almost surely, 2^81415523 is an apocalyptic number.

81415523 is a deficient number, since it is larger than the sum of its proper divisors (11630797).

81415523 is a wasteful number, since it uses less digits than its factorization.

81415523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11630796.

The product of its digits is 4800, while the sum is 29.

The square root of 81415523 is about 9023.0550812904. The cubic root of 81415523 is about 433.4134711092.

The spelling of 81415523 in words is "eighty-one million, four hundred fifteen thousand, five hundred twenty-three".