81723623 has 6 divisors (see below), whose sum is σ = 85431864. Its totient is φ = 78169916.

The previous prime is 81723601. The next prime is 81723679. The reversal of 81723623 is 32632718.

It is a happy number.

It is not a de Polignac number, because 81723623 - 2⁶ = 81723559 is a prime.

It is a super-2 number, since 2×81723623² = 13357501112492258, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81723623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81720623) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 76715 + ... + 77772.

It is an arithmetic number, because the mean of its divisors is an integer number (14238644).

Almost surely, 2^81723623 is an apocalyptic number.

81723623 is a deficient number, since it is larger than the sum of its proper divisors (3708241).

81723623 is a wasteful number, since it uses less digits than its factorization.

81723623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154533 (or 154510 counting only the distinct ones).

The product of its digits is 12096, while the sum is 32.

The square root of 81723623 is about 9040.1118909005. Note that the first 3 decimals coincide. The cubic root of 81723623 is about 433.9595037497.

The spelling of 81723623 in words is "eighty-one million, seven hundred twenty-three thousand, six hundred twenty-three".