81040709 has 4 divisors (see below), whose sum is σ = 81827616. Its totient is φ = 80253804.

The previous prime is 81040699. The next prime is 81040711. The reversal of 81040709 is 90704018.

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 81040709 - 2¹⁶ = 80975173 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81040769) 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, 393299 + ... + 393504.

It is an arithmetic number, because the mean of its divisors is an integer number (20456904).

Almost surely, 2^81040709 is an apocalyptic number.

It is an amenable number.

81040709 is a deficient number, since it is larger than the sum of its proper divisors (786907).

81040709 is a wasteful number, since it uses less digits than its factorization.

81040709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 786906.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 81040709 is about 9002.2613270222. The cubic root of 81040709 is about 432.7473435670.

The spelling of 81040709 in words is "eighty-one million, forty thousand, seven hundred nine".