81339263 has 4 divisors (see below), whose sum is σ = 81373248. Its totient is φ = 81305280.

The previous prime is 81339221. The next prime is 81339277. The reversal of 81339263 is 36293318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36293318 = 2 ⋅18146659.

It is a cyclic number.

It is not a de Polignac number, because 81339263 - 2⁶ = 81339199 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 (81339163) 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, 13106 + ... + 18287.

It is an arithmetic number, because the mean of its divisors is an integer number (20343312).

Almost surely, 2^81339263 is an apocalyptic number.

81339263 is a deficient number, since it is larger than the sum of its proper divisors (33985).

81339263 is a wasteful number, since it uses less digits than its factorization.

81339263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33984.

The product of its digits is 23328, while the sum is 35.

The square root of 81339263 is about 9018.8282498338. The cubic root of 81339263 is about 433.2781061110.

The spelling of 81339263 in words is "eighty-one million, three hundred thirty-nine thousand, two hundred sixty-three".