81852191 has 4 divisors (see below), whose sum is σ = 81900792. Its totient is φ = 81803592.

The previous prime is 81852167. The next prime is 81852223. The reversal of 81852191 is 19125818.

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

It is a cyclic number.

It is not a de Polignac number, because 81852191 - 2¹⁰ = 81851167 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 (81852131) 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, 21680 + ... + 25173.

It is an arithmetic number, because the mean of its divisors is an integer number (20475198).

Almost surely, 2^81852191 is an apocalyptic number.

81852191 is a deficient number, since it is larger than the sum of its proper divisors (48601).

81852191 is a wasteful number, since it uses less digits than its factorization.

81852191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48600.

The product of its digits is 5760, while the sum is 35.

The square root of 81852191 is about 9047.2200702757. The cubic root of 81852191 is about 434.1869535816.

The spelling of 81852191 in words is "eighty-one million, eight hundred fifty-two thousand, one hundred ninety-one".