81455391 has 6 divisors (see below), whose sum is σ = 117657800. Its totient is φ = 54303588.

The previous prime is 81455323. The next prime is 81455393. The reversal of 81455391 is 19355418.

81455391 is a `hidden beast` number, since 8 + 14 + 553 + 91 = 666.

It is not a de Polignac number, because 81455391 - 2¹⁷ = 81324319 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 (81455393) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4525291 + ... + 4525308.

Almost surely, 2^81455391 is an apocalyptic number.

81455391 is a deficient number, since it is larger than the sum of its proper divisors (36202409).

81455391 is a wasteful number, since it uses less digits than its factorization.

81455391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9050605 (or 9050602 counting only the distinct ones).

The product of its digits is 21600, while the sum is 36.

The square root of 81455391 is about 9025.2640404589. The cubic root of 81455391 is about 433.4842049936.

The spelling of 81455391 in words is "eighty-one million, four hundred fifty-five thousand, three hundred ninety-one".