81390759 has 8 divisors (see below), whose sum is σ = 108563952. Its totient is φ = 54239040.

The previous prime is 81390731. The next prime is 81390769. The reversal of 81390759 is 95709318.

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 81390759 - 2⁸ = 81390503 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81390759.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390709) 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, 8889 + ... + 15549.

It is an arithmetic number, because the mean of its divisors is an integer number (13570494).

Almost surely, 2^81390759 is an apocalyptic number.

81390759 is a deficient number, since it is larger than the sum of its proper divisors (27173193).

81390759 is a wasteful number, since it uses less digits than its factorization.

81390759 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10737.

The product of its (nonzero) digits is 68040, while the sum is 42.

The square root of 81390759 is about 9021.6827144386. The cubic root of 81390759 is about 433.3695231445.

The spelling of 81390759 in words is "eighty-one million, three hundred ninety thousand, seven hundred fifty-nine".