81813474 has 12 divisors (see below), whose sum is σ = 177262566. Its totient is φ = 27271152.

The previous prime is 81813439. The next prime is 81813551. The reversal of 81813474 is 47431818.

81813474 is a `hidden beast` number, since 8 + 181 + 3 + 474 = 666.

It can be written as a sum of positive squares in only one way, i.e., 50509449 + 31304025 = 7107^2 + 5595^2 .

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 an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2272579 + ... + 2272614.

Almost surely, 2^81813474 is an apocalyptic number.

81813474 is an abundant number, since it is smaller than the sum of its proper divisors (95449092).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81813474 is a wasteful number, since it uses less digits than its factorization.

81813474 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4545201 (or 4545198 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 81813474 is about 9045.0800991478. The cubic root of 81813474 is about 434.1184843597.

The spelling of 81813474 in words is "eighty-one million, eight hundred thirteen thousand, four hundred seventy-four".