81724825 has 24 divisors (see below), whose sum is σ = 124728128. Its totient is φ = 51727680.

The previous prime is 81724801. The next prime is 81724829. The reversal of 81724825 is 52842718.

It is not a de Polignac number, because 81724825 - 2¹¹ = 81722777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81724829) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15687 + ... + 20236.

Almost surely, 2^81724825 is an apocalyptic number.

It is an amenable number.

81724825 is a deficient number, since it is larger than the sum of its proper divisors (43003303).

81724825 is a wasteful number, since it uses less digits than its factorization.

81724825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35953 (or 35948 counting only the distinct ones).

The product of its digits is 35840, while the sum is 37.

The square root of 81724825 is about 9040.1783721340. The cubic root of 81724825 is about 433.9616313139.

The spelling of 81724825 in words is "eighty-one million, seven hundred twenty-four thousand, eight hundred twenty-five".