81885813 has 4 divisors (see below), whose sum is σ = 109181088. Its totient is φ = 54590540.

The previous prime is 81885799. The next prime is 81885841. The reversal of 81885813 is 31858818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81885813 - 2¹⁴ = 81869429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81885863) 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, 13647633 + ... + 13647638.

It is an arithmetic number, because the mean of its divisors is an integer number (27295272).

Almost surely, 2^81885813 is an apocalyptic number.

It is an amenable number.

81885813 is a deficient number, since it is larger than the sum of its proper divisors (27295275).

81885813 is a wasteful number, since it uses less digits than its factorization.

81885813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27295274.

The product of its digits is 61440, while the sum is 42.

The square root of 81885813 is about 9049.0780193343. The cubic root of 81885813 is about 434.2463950179.

The spelling of 81885813 in words is "eighty-one million, eight hundred eighty-five thousand, eight hundred thirteen".