81724605 has 16 divisors (see below), whose sum is σ = 137641920. Its totient is φ = 41292288.

The previous prime is 81724597. The next prime is 81724607. The reversal of 81724605 is 50642718.

It is not a de Polignac number, because 81724605 - 2³ = 81724597 is a prime.

It is a super-2 number, since 2×81724605² = 13357822124812050, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81724607) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143092 + ... + 143661.

It is an arithmetic number, because the mean of its divisors is an integer number (8602620).

Almost surely, 2^81724605 is an apocalyptic number.

It is an amenable number.

81724605 is a deficient number, since it is larger than the sum of its proper divisors (55917315).

81724605 is a wasteful number, since it uses less digits than its factorization.

81724605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286780.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 81724605 is about 9040.1662042243. The cubic root of 81724605 is about 433.9612419111.

The spelling of 81724605 in words is "eighty-one million, seven hundred twenty-four thousand, six hundred five".