81893149 has 4 divisors (see below), whose sum is σ = 88192636. Its totient is φ = 75593664.

The previous prime is 81893143. The next prime is 81893153. The reversal of 81893149 is 94139818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53728900 + 28164249 = 7330^2 + 5307^2 .

It is a cyclic number.

It is not a de Polignac number, because 81893149 - 2⁹ = 81892637 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 (81893143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3149724 + ... + 3149749.

It is an arithmetic number, because the mean of its divisors is an integer number (22048159).

Almost surely, 2^81893149 is an apocalyptic number.

It is an amenable number.

81893149 is a deficient number, since it is larger than the sum of its proper divisors (6299487).

81893149 is a wasteful number, since it uses less digits than its factorization.

81893149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6299486.

The product of its digits is 62208, while the sum is 43.

The square root of 81893149 is about 9049.4833554187. The cubic root of 81893149 is about 434.2593624104.

The spelling of 81893149 in words is "eighty-one million, eight hundred ninety-three thousand, one hundred forty-nine".