81371889 has 12 divisors (see below), whose sum is σ = 123723600. Its totient is φ = 51392664.

The previous prime is 81371881. The next prime is 81371897. The reversal of 81371889 is 98817318.

It is an interprime number because it is at equal distance from previous prime (81371881) and next prime (81371897).

It is not a de Polignac number, because 81371889 - 2³ = 81371881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81371881) 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, 237759 + ... + 238100.

It is an arithmetic number, because the mean of its divisors is an integer number (10310300).

Almost surely, 2^81371889 is an apocalyptic number.

It is an amenable number.

81371889 is a deficient number, since it is larger than the sum of its proper divisors (42351711).

81371889 is a wasteful number, since it uses less digits than its factorization.

81371889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475884 (or 475881 counting only the distinct ones).

The product of its digits is 96768, while the sum is 45.

The square root of 81371889 is about 9020.6368400463. The cubic root of 81371889 is about 433.3360291088.

The spelling of 81371889 in words is "eighty-one million, three hundred seventy-one thousand, eight hundred eighty-nine".