81438394 has 8 divisors (see below), whose sum is σ = 122261940. Its totient is φ = 40684416.

The previous prime is 81438391. The next prime is 81438403. The reversal of 81438394 is 49383418.

It can be written as a sum of positive squares in 2 ways, for example, as 58752225 + 22686169 = 7665^2 + 4763^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81438391) 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, 14359 + ... + 19210.

Almost surely, 2^81438394 is an apocalyptic number.

81438394 is a deficient number, since it is larger than the sum of its proper divisors (40823546).

81438394 is a wasteful number, since it uses less digits than its factorization.

81438394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34784.

The product of its digits is 82944, while the sum is 40.

The square root of 81438394 is about 9024.3223568310. The cubic root of 81438394 is about 433.4540517056.

The spelling of 81438394 in words is "eighty-one million, four hundred thirty-eight thousand, three hundred ninety-four".