81315469 has 2 divisors, whose sum is σ = 81315470. Its totient is φ = 81315468.

The previous prime is 81315461. The next prime is 81315523. The reversal of 81315469 is 96451318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80335369 + 980100 = 8963^2 + 990^2 .

It is a cyclic number.

It is not a de Polignac number, because 81315469 - 2³ = 81315461 is a prime.

It is a super-2 number, since 2×81315469² = 13224410997379922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81315461) 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, 40657734 + 40657735.

It is an arithmetic number, because the mean of its divisors is an integer number (40657735).

Almost surely, 2^81315469 is an apocalyptic number.

It is an amenable number.

81315469 is a deficient number, since it is larger than the sum of its proper divisors (1).

81315469 is an equidigital number, since it uses as much as digits as its factorization.

81315469 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 37.

The square root of 81315469 is about 9017.5090241153. The cubic root of 81315469 is about 433.2358533526.

The spelling of 81315469 in words is "eighty-one million, three hundred fifteen thousand, four hundred sixty-nine".