81315523 has 2 divisors, whose sum is σ = 81315524. Its totient is φ = 81315522.

The previous prime is 81315469. The next prime is 81315527. The reversal of 81315523 is 32551318.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81315523 is a prime.

It is a super-2 number, since 2×81315523² = 13224428561527058, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81315491 and 81315500.

It is not a weakly prime, because it can be changed into another prime (81315527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40657761 + 40657762.

It is an arithmetic number, because the mean of its divisors is an integer number (40657762).

Almost surely, 2^81315523 is an apocalyptic number.

81315523 is a deficient number, since it is larger than the sum of its proper divisors (1).

81315523 is an equidigital number, since it uses as much as digits as its factorization.

81315523 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 28.

The square root of 81315523 is about 9017.5120182897. The cubic root of 81315523 is about 433.2359492537.

The spelling of 81315523 in words is "eighty-one million, three hundred fifteen thousand, five hundred twenty-three".