81381159 has 16 divisors (see below), whose sum is σ = 127657440. Its totient is φ = 51062400.

The previous prime is 81381073. The next prime is 81381197. The reversal of 81381159 is 95118318.

It is not a de Polignac number, because 81381159 - 2⁷ = 81381031 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81381059) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 88192 + ... + 89109.

It is an arithmetic number, because the mean of its divisors is an integer number (7978590).

Almost surely, 2^81381159 is an apocalyptic number.

81381159 is a deficient number, since it is larger than the sum of its proper divisors (46276281).

81381159 is a wasteful number, since it uses less digits than its factorization.

81381159 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177327 (or 177321 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 81381159 is about 9021.1506472290. The cubic root of 81381159 is about 433.3524839005.

The spelling of 81381159 in words is "eighty-one million, three hundred eighty-one thousand, one hundred fifty-nine".