81242393 has 4 divisors (see below), whose sum is σ = 81691428. Its totient is φ = 80793360.

The previous prime is 81242353. The next prime is 81242419. The reversal of 81242393 is 39324218.

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 32410249 + 48832144 = 5693^2 + 6988^2 .

It is a cyclic number.

It is not a de Polignac number, because 81242393 - 2¹⁶ = 81176857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81242353) 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, 224246 + ... + 224607.

It is an arithmetic number, because the mean of its divisors is an integer number (20422857).

Almost surely, 2^81242393 is an apocalyptic number.

It is an amenable number.

81242393 is a deficient number, since it is larger than the sum of its proper divisors (449035).

81242393 is a wasteful number, since it uses less digits than its factorization.

81242393 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449034.

The product of its digits is 10368, while the sum is 32.

The square root of 81242393 is about 9013.4562183438. The cubic root of 81242393 is about 433.1060353647.

The spelling of 81242393 in words is "eighty-one million, two hundred forty-two thousand, three hundred ninety-three".