81415975 has 24 divisors (see below), whose sum is σ = 111555360. Its totient is φ = 58629120.

The previous prime is 81415903. The next prime is 81415991. The reversal of 81415975 is 57951418.

It is a happy number.

It is not a de Polignac number, because 81415975 - 2¹³ = 81407783 is a prime.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5611 + ... + 13939.

It is an arithmetic number, because the mean of its divisors is an integer number (4648140).

Almost surely, 2^81415975 is an apocalyptic number.

81415975 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81415975 is a deficient number, since it is larger than the sum of its proper divisors (30139385).

81415975 is a wasteful number, since it uses less digits than its factorization.

81415975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8379 (or 8374 counting only the distinct ones).

The product of its digits is 50400, while the sum is 40.

The square root of 81415975 is about 9023.0801282046. The cubic root of 81415975 is about 433.4142731779.

The spelling of 81415975 in words is "eighty-one million, four hundred fifteen thousand, nine hundred seventy-five".