81849381 has 4 divisors (see below), whose sum is σ = 109132512. Its totient is φ = 54566252.

The previous prime is 81849377. The next prime is 81849389. The reversal of 81849381 is 18394818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81849381 - 2² = 81849377 is a prime.

It is a super-2 number, since 2×81849381² = 13398642340166322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81849389) 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, 13641561 + ... + 13641566.

It is an arithmetic number, because the mean of its divisors is an integer number (27283128).

Almost surely, 2^81849381 is an apocalyptic number.

It is an amenable number.

81849381 is a deficient number, since it is larger than the sum of its proper divisors (27283131).

81849381 is a wasteful number, since it uses less digits than its factorization.

81849381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27283130.

The product of its digits is 55296, while the sum is 42.

The square root of 81849381 is about 9047.0647726210. The cubic root of 81849381 is about 434.1819849534.

The spelling of 81849381 in words is "eighty-one million, eight hundred forty-nine thousand, three hundred eighty-one".