81723311 has 4 divisors (see below), whose sum is σ = 81908232. Its totient is φ = 81538392.

The previous prime is 81723307. The next prime is 81723329. The reversal of 81723311 is 11332718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81723311 - 2² = 81723307 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 (81723331) 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, 91796 + ... + 92681.

It is an arithmetic number, because the mean of its divisors is an integer number (20477058).

Almost surely, 2^81723311 is an apocalyptic number.

81723311 is a deficient number, since it is larger than the sum of its proper divisors (184921).

81723311 is a wasteful number, since it uses less digits than its factorization.

81723311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184920.

The product of its digits is 1008, while the sum is 26.

The square root of 81723311 is about 9040.0946344604. The cubic root of 81723311 is about 433.9589515000.

The spelling of 81723311 in words is "eighty-one million, seven hundred twenty-three thousand, three hundred eleven".