81793381 has 4 divisors (see below), whose sum is σ = 81910764. Its totient is φ = 81676000.

The previous prime is 81793379. The next prime is 81793441. The reversal of 81793381 is 18339718.

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 76842756 + 4950625 = 8766^2 + 2225^2 .

It is a cyclic number.

It is not a de Polignac number, because 81793381 - 2¹ = 81793379 is a prime.

It is a super-2 number, since 2×81793381² = 13380314350822322, 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 (81793351) 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, 57640 + ... + 59041.

It is an arithmetic number, because the mean of its divisors is an integer number (20477691).

Almost surely, 2^81793381 is an apocalyptic number.

It is an amenable number.

81793381 is a deficient number, since it is larger than the sum of its proper divisors (117383).

81793381 is a wasteful number, since it uses less digits than its factorization.

81793381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117382.

The product of its digits is 36288, while the sum is 40.

The square root of 81793381 is about 9043.9693166220. The cubic root of 81793381 is about 434.0829423050.

The spelling of 81793381 in words is "eighty-one million, seven hundred ninety-three thousand, three hundred eighty-one".