81130381 has 4 divisors (see below), whose sum is σ = 83323132. Its totient is φ = 78937632.

The previous prime is 81130373. The next prime is 81130411. The reversal of 81130381 is 18303118.

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 44769481 + 36360900 = 6691^2 + 6030^2 .

It is a cyclic number.

It is not a de Polignac number, because 81130381 - 2³ = 81130373 is a prime.

It is a super-2 number, since 2×81130381² = 13164277442410322, 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 (81130321) 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, 1096320 + ... + 1096393.

It is an arithmetic number, because the mean of its divisors is an integer number (20830783).

Almost surely, 2^81130381 is an apocalyptic number.

It is an amenable number.

81130381 is a deficient number, since it is larger than the sum of its proper divisors (2192751).

81130381 is a wasteful number, since it uses less digits than its factorization.

81130381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2192750.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 81130381 is about 9007.2404764167. The cubic root of 81130381 is about 432.9068971885.

Adding to 81130381 its reverse (18303118), we get a palindrome (99433499).

The spelling of 81130381 in words is "eighty-one million, one hundred thirty thousand, three hundred eighty-one".