81390093 has 4 divisors (see below), whose sum is σ = 108520128. Its totient is φ = 54260060.

The previous prime is 81390083. The next prime is 81390103. The reversal of 81390093 is 39009318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (81390083) and next prime (81390103).

It is a cyclic number.

It is not a de Polignac number, because 81390093 - 2⁵ = 81390061 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390073) 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, 13565013 + ... + 13565018.

It is an arithmetic number, because the mean of its divisors is an integer number (27130032).

Almost surely, 2^81390093 is an apocalyptic number.

It is an amenable number.

81390093 is a deficient number, since it is larger than the sum of its proper divisors (27130035).

81390093 is a wasteful number, since it uses less digits than its factorization.

81390093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27130034.

The product of its (nonzero) digits is 5832, while the sum is 33.

The square root of 81390093 is about 9021.6458032889. The cubic root of 81390093 is about 433.3683410902.

The spelling of 81390093 in words is "eighty-one million, three hundred ninety thousand, ninety-three".