81825399 has 24 divisors (see below), whose sum is σ = 122525312. Its totient is φ = 52565760.

The previous prime is 81825397. The next prime is 81825413. The reversal of 81825399 is 99352818.

It is a happy number.

It is not a de Polignac number, because 81825399 - 2¹ = 81825397 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 (81825397) 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, 86859 + ... + 87795.

Almost surely, 2^81825399 is an apocalyptic number.

81825399 is a deficient number, since it is larger than the sum of its proper divisors (40699913).

81825399 is a wasteful number, since it uses less digits than its factorization.

81825399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1287 (or 1284 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 81825399 is about 9045.7392732711. The cubic root of 81825399 is about 434.1395754716.

The spelling of 81825399 in words is "eighty-one million, eight hundred twenty-five thousand, three hundred ninety-nine".