81138851 has 8 divisors (see below), whose sum is σ = 82155360. Its totient is φ = 80126208.

The previous prime is 81138833. The next prime is 81138853. The reversal of 81138851 is 15883118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81138851 - 2¹⁰ = 81137827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81138853) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80885 + ... + 81881.

It is an arithmetic number, because the mean of its divisors is an integer number (10269420).

Almost surely, 2^81138851 is an apocalyptic number.

81138851 is a deficient number, since it is larger than the sum of its proper divisors (1016509).

81138851 is an equidigital number, since it uses as much as digits as its factorization.

81138851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1933.

The product of its digits is 7680, while the sum is 35.

The square root of 81138851 is about 9007.7106414449. The cubic root of 81138851 is about 432.9219618033.

The spelling of 81138851 in words is "eighty-one million, one hundred thirty-eight thousand, eight hundred fifty-one".