81452381 has 4 divisors (see below), whose sum is σ = 81475164. Its totient is φ = 81429600.

The previous prime is 81452333. The next prime is 81452401. The reversal of 81452381 is 18325418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18325418 = 2 ⋅9162709.

It can be written as a sum of positive squares in 2 ways, for example, as 18567481 + 62884900 = 4309^2 + 7930^2 .

It is a cyclic number.

It is not a de Polignac number, because 81452381 - 2¹⁸ = 81190237 is a prime.

It is a super-2 number, since 2×81452381² = 13268980741138322, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81454381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4730 + ... + 13611.

It is an arithmetic number, because the mean of its divisors is an integer number (20368791).

Almost surely, 2^81452381 is an apocalyptic number.

It is an amenable number.

81452381 is a deficient number, since it is larger than the sum of its proper divisors (22783).

81452381 is a wasteful number, since it uses less digits than its factorization.

81452381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22782.

The product of its digits is 7680, while the sum is 32.

The square root of 81452381 is about 9025.0972847942. The cubic root of 81452381 is about 433.4788654512.

Adding to 81452381 its reverse (18325418), we get a palindrome (99777799).

The spelling of 81452381 in words is "eighty-one million, four hundred fifty-two thousand, three hundred eighty-one".