81398831 has 8 divisors (see below), whose sum is σ = 87300720. Its totient is φ = 75658752.

The previous prime is 81398809. The next prime is 81398857. The reversal of 81398831 is 13889318.

It is a happy number.

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 81398831 - 2⁶ = 81398767 is a prime.

It is a super-2 number, since 2×81398831² = 13251539376333122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81398881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39410 + ... + 41423.

It is an arithmetic number, because the mean of its divisors is an integer number (10912590).

Almost surely, 2^81398831 is an apocalyptic number.

81398831 is a deficient number, since it is larger than the sum of its proper divisors (5901889).

81398831 is a wasteful number, since it uses less digits than its factorization.

81398831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80905.

The product of its digits is 41472, while the sum is 41.

The square root of 81398831 is about 9022.1300700001. The cubic root of 81398831 is about 433.3838492719.

The spelling of 81398831 in words is "eighty-one million, three hundred ninety-eight thousand, eight hundred thirty-one".