81399039 has 8 divisors (see below), whose sum is σ = 108600240. Its totient is φ = 54231936.

The previous prime is 81399011. The next prime is 81399041. The reversal of 81399039 is 93099318.

It is a happy number.

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

It is not a de Polignac number, because 81399039 - 2²⁵ = 47844607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81399239) 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, 2304 + ... + 12965.

It is an arithmetic number, because the mean of its divisors is an integer number (13575030).

Almost surely, 2^81399039 is an apocalyptic number.

81399039 is a deficient number, since it is larger than the sum of its proper divisors (27201201).

81399039 is a wasteful number, since it uses less digits than its factorization.

81399039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17049.

The product of its (nonzero) digits is 52488, while the sum is 42.

The square root of 81399039 is about 9022.1415972041. The cubic root of 81399039 is about 433.3842184163.

The spelling of 81399039 in words is "eighty-one million, three hundred ninety-nine thousand, thirty-nine".