81171387 has 12 divisors (see below), whose sum is σ = 127906584. Its totient is φ = 49194720.

The previous prime is 81171329. The next prime is 81171407. The reversal of 81171387 is 78317118.

It is not a de Polignac number, because 81171387 - 2⁶ = 81171323 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81171317) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 409858 + ... + 410055.

It is an arithmetic number, because the mean of its divisors is an integer number (10658882).

Almost surely, 2^81171387 is an apocalyptic number.

81171387 is a deficient number, since it is larger than the sum of its proper divisors (46735197).

81171387 is a wasteful number, since it uses less digits than its factorization.

81171387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819930 (or 819927 counting only the distinct ones).

The product of its digits is 9408, while the sum is 36.

The square root of 81171387 is about 9009.5164687124. The cubic root of 81171387 is about 432.9798200979.

The spelling of 81171387 in words is "eighty-one million, one hundred seventy-one thousand, three hundred eighty-seven".