81440093 has 4 divisors (see below), whose sum is σ = 93074400. Its totient is φ = 69805788.

The previous prime is 81440089. The next prime is 81440101. The reversal of 81440093 is 39004418.

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 a cyclic number.

It is not a de Polignac number, because 81440093 - 2² = 81440089 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 (81440003) 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, 5817143 + ... + 5817156.

It is an arithmetic number, because the mean of its divisors is an integer number (23268600).

Almost surely, 2^81440093 is an apocalyptic number.

It is an amenable number.

81440093 is a deficient number, since it is larger than the sum of its proper divisors (11634307).

81440093 is a wasteful number, since it uses less digits than its factorization.

81440093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11634306.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 81440093 is about 9024.4164908320. The cubic root of 81440093 is about 433.4570659813.

The spelling of 81440093 in words is "eighty-one million, four hundred forty thousand, ninety-three".