81538379 has 4 divisors (see below), whose sum is σ = 87810576. Its totient is φ = 75266184.

The previous prime is 81538361. The next prime is 81538399. The reversal of 81538379 is 97383518.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81538379 - 2⁸ = 81538123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81538309) 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, 3136079 + ... + 3136104.

It is an arithmetic number, because the mean of its divisors is an integer number (21952644).

Almost surely, 2^81538379 is an apocalyptic number.

81538379 is a deficient number, since it is larger than the sum of its proper divisors (6272197).

81538379 is a wasteful number, since it uses less digits than its factorization.

81538379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6272196.

The product of its digits is 181440, while the sum is 44.

The square root of 81538379 is about 9029.8604086663. The cubic root of 81538379 is about 433.6313684766.

The spelling of 81538379 in words is "eighty-one million, five hundred thirty-eight thousand, three hundred seventy-nine".