81908297 has 4 divisors (see below), whose sum is σ = 86219280. Its totient is φ = 77597316.

The previous prime is 81908291. The next prime is 81908303. The reversal of 81908297 is 79280918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (81908291) and next prime (81908303).

It is a cyclic number.

It is not a de Polignac number, because 81908297 - 2⁸ = 81908041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81908291) 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, 2155463 + ... + 2155500.

It is an arithmetic number, because the mean of its divisors is an integer number (21554820).

Almost surely, 2^81908297 is an apocalyptic number.

It is an amenable number.

81908297 is a deficient number, since it is larger than the sum of its proper divisors (4310983).

81908297 is a wasteful number, since it uses less digits than its factorization.

81908297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310982.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 81908297 is about 9050.3202705761. The cubic root of 81908297 is about 434.2861361407.

The spelling of 81908297 in words is "eighty-one million, nine hundred eight thousand, two hundred ninety-seven".