81320291 has 8 divisors (see below), whose sum is σ = 87647280. Its totient is φ = 75003552.

The previous prime is 81320273. The next prime is 81320297. The reversal of 81320291 is 19202318.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81320291 - 2¹⁰ = 81319267 is a prime.

It is a super-2 number, since 2×81320291² = 13225979456649362, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81320291.

It is not an unprimeable number, because it can be changed into a prime (81320297) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24836 + ... + 27918.

It is an arithmetic number, because the mean of its divisors is an integer number (10955910).

Almost surely, 2^81320291 is an apocalyptic number.

81320291 is a deficient number, since it is larger than the sum of its proper divisors (6326989).

81320291 is a wasteful number, since it uses less digits than its factorization.

81320291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5125.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 81320291 is about 9017.7763888888. The cubic root of 81320291 is about 433.2444167990.

The spelling of 81320291 in words is "eighty-one million, three hundred twenty thousand, two hundred ninety-one".