81438375 has 16 divisors (see below), whose sum is σ = 135514080. Its totient is φ = 43433600.

The previous prime is 81438373. The next prime is 81438391. The reversal of 81438375 is 57383418.

It is not a de Polignac number, because 81438375 - 2¹ = 81438373 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81438373) 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, 108210 + ... + 108959.

It is an arithmetic number, because the mean of its divisors is an integer number (8469630).

Almost surely, 2^81438375 is an apocalyptic number.

81438375 is a deficient number, since it is larger than the sum of its proper divisors (54075705).

81438375 is a wasteful number, since it uses less digits than its factorization.

81438375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217187 (or 217177 counting only the distinct ones).

The product of its digits is 80640, while the sum is 39.

The square root of 81438375 is about 9024.3213041203. The cubic root of 81438375 is about 433.4540179966.

The spelling of 81438375 in words is "eighty-one million, four hundred thirty-eight thousand, three hundred seventy-five".