81986397 has 4 divisors (see below), whose sum is σ = 109315200. Its totient is φ = 54657596.

The previous prime is 81986369. The next prime is 81986419. The reversal of 81986397 is 79368918.

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 81986397 - 2⁷ = 81986269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81986357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13664397 + ... + 13664402.

It is an arithmetic number, because the mean of its divisors is an integer number (27328800).

Almost surely, 2^81986397 is an apocalyptic number.

It is an amenable number.

81986397 is a deficient number, since it is larger than the sum of its proper divisors (27328803).

81986397 is a wasteful number, since it uses less digits than its factorization.

81986397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27328802.

The product of its digits is 653184, while the sum is 51.

The square root of 81986397 is about 9054.6340069602. The cubic root of 81986397 is about 434.4241236785.

The spelling of 81986397 in words is "eighty-one million, nine hundred eighty-six thousand, three hundred ninety-seven".