81089381 has 4 divisors (see below), whose sum is σ = 81925452. Its totient is φ = 80253312.

The previous prime is 81089377. The next prime is 81089383. The reversal of 81089381 is 18398018.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18398018 = 2 ⋅9199009.

It can be written as a sum of positive squares in 2 ways, for example, as 43020481 + 38068900 = 6559^2 + 6170^2 .

It is a cyclic number.

It is not a de Polignac number, because 81089381 - 2² = 81089377 is a prime.

It is a super-2 number, since 2×81089381² = 13150975421926322, 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 (81089383) 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, 417890 + ... + 418083.

It is an arithmetic number, because the mean of its divisors is an integer number (20481363).

Almost surely, 2^81089381 is an apocalyptic number.

It is an amenable number.

81089381 is a deficient number, since it is larger than the sum of its proper divisors (836071).

81089381 is an equidigital number, since it uses as much as digits as its factorization.

81089381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 836070.

The product of its (nonzero) digits is 13824, while the sum is 38.

The square root of 81089381 is about 9004.9642420167. The cubic root of 81089381 is about 432.8339603786.

The spelling of 81089381 in words is "eighty-one million, eighty-nine thousand, three hundred eighty-one".