81924365 has 4 divisors (see below), whose sum is σ = 98309244. Its totient is φ = 65539488.

The previous prime is 81924361. The next prime is 81924373. The reversal of 81924365 is 56342918.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 26853124 + 55071241 = 5182^2 + 7421^2 .

It is a cyclic number.

It is not a de Polignac number, because 81924365 - 2² = 81924361 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81924361) 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, 8192432 + ... + 8192441.

It is an arithmetic number, because the mean of its divisors is an integer number (24577311).

Almost surely, 2^81924365 is an apocalyptic number.

It is an amenable number.

81924365 is a deficient number, since it is larger than the sum of its proper divisors (16384879).

81924365 is a wasteful number, since it uses less digits than its factorization.

81924365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16384878.

The product of its digits is 51840, while the sum is 38.

The square root of 81924365 is about 9051.2079304367. The cubic root of 81924365 is about 434.3145323417.

The spelling of 81924365 in words is "eighty-one million, nine hundred twenty-four thousand, three hundred sixty-five".