81797591 has 8 divisors (see below), whose sum is σ = 90375264. Its totient is φ = 73638400.

The previous prime is 81797539. The next prime is 81797593. The reversal of 81797591 is 19579718.

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

It is a cyclic number.

It is not a de Polignac number, because 81797591 - 2¹⁴ = 81781207 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81797593) 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, 104210 + ... + 104991.

It is an arithmetic number, because the mean of its divisors is an integer number (11296908).

Almost surely, 2^81797591 is an apocalyptic number.

81797591 is a deficient number, since it is larger than the sum of its proper divisors (8577673).

81797591 is a wasteful number, since it uses less digits than its factorization.

81797591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209241.

The product of its digits is 158760, while the sum is 47.

The square root of 81797591 is about 9044.2020654119. The cubic root of 81797591 is about 434.0903897611.

The spelling of 81797591 in words is "eighty-one million, seven hundred ninety-seven thousand, five hundred ninety-one".