81571397 has 4 divisors (see below), whose sum is σ = 81602400. Its totient is φ = 81540396.

The previous prime is 81571331. The next prime is 81571433. The reversal of 81571397 is 79317518.

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 a cyclic number.

It is not a de Polignac number, because 81571397 - 2⁸ = 81571141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81571327) 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, 11147 + ... + 16952.

It is an arithmetic number, because the mean of its divisors is an integer number (20400600).

Almost surely, 2^81571397 is an apocalyptic number.

It is an amenable number.

81571397 is a deficient number, since it is larger than the sum of its proper divisors (31003).

81571397 is a wasteful number, since it uses less digits than its factorization.

81571397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31002.

The product of its digits is 52920, while the sum is 41.

The square root of 81571397 is about 9031.6884910852. The cubic root of 81571397 is about 433.6898918720.

The spelling of 81571397 in words is "eighty-one million, five hundred seventy-one thousand, three hundred ninety-seven".