81343391 has 4 divisors (see below), whose sum is σ = 81792984. Its totient is φ = 80893800.

The previous prime is 81343369. The next prime is 81343397. The reversal of 81343391 is 19334318.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19334318 = 2 ⋅9667159.

It is a cyclic number.

It is not a de Polignac number, because 81343391 - 2²⁶ = 14234527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81343397) 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, 224525 + ... + 224886.

It is an arithmetic number, because the mean of its divisors is an integer number (20448246).

Almost surely, 2^81343391 is an apocalyptic number.

81343391 is a deficient number, since it is larger than the sum of its proper divisors (449593).

81343391 is a wasteful number, since it uses less digits than its factorization.

81343391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449592.

The product of its digits is 7776, while the sum is 32.

The square root of 81343391 is about 9019.0571014935. The cubic root of 81343391 is about 433.2854356658.

The spelling of 81343391 in words is "eighty-one million, three hundred forty-three thousand, three hundred ninety-one".