81422381 has 4 divisors (see below), whose sum is σ = 81440700. Its totient is φ = 81404064.

The previous prime is 81422339. The next prime is 81422389. The reversal of 81422381 is 18322418.

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

It can be written as a sum of positive squares in 2 ways, for example, as 24344356 + 57078025 = 4934^2 + 7555^2 .

It is a cyclic number.

It is not a de Polignac number, because 81422381 - 2¹⁴ = 81405997 is a prime.

It is a super-2 number, since 2×81422381² = 13259208255418322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81422389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2225 + ... + 12953.

It is an arithmetic number, because the mean of its divisors is an integer number (20360175).

Almost surely, 2^81422381 is an apocalyptic number.

It is an amenable number.

81422381 is a deficient number, since it is larger than the sum of its proper divisors (18319).

81422381 is a wasteful number, since it uses less digits than its factorization.

81422381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18318.

The product of its digits is 3072, while the sum is 29.

The square root of 81422381 is about 9023.4350997832. The cubic root of 81422381 is about 433.4256402306.

Adding to 81422381 its reverse (18322418), we get a palindrome (99744799).

The spelling of 81422381 in words is "eighty-one million, four hundred twenty-two thousand, three hundred eighty-one".