81438193 has 16 divisors (see below), whose sum is σ = 86760576. Its totient is φ = 76285440.

The previous prime is 81438191. The next prime is 81438229. The reversal of 81438193 is 39183418.

It is a cyclic number.

It is not a de Polignac number, because 81438193 - 2¹ = 81438191 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81438191) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 385858 + ... + 386068.

It is an arithmetic number, because the mean of its divisors is an integer number (5422536).

Almost surely, 2^81438193 is an apocalyptic number.

It is an amenable number.

81438193 is a deficient number, since it is larger than the sum of its proper divisors (5322383).

81438193 is a wasteful number, since it uses less digits than its factorization.

81438193 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504.

The product of its digits is 20736, while the sum is 37.

The square root of 81438193 is about 9024.3112202539. The cubic root of 81438193 is about 433.4536950993.

The spelling of 81438193 in words is "eighty-one million, four hundred thirty-eight thousand, one hundred ninety-three".