81380239 has 4 divisors (see below), whose sum is σ = 84005440. Its totient is φ = 78755040.

The previous prime is 81380153. The next prime is 81380251. The reversal of 81380239 is 93208318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81380239 - 2⁷ = 81380111 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 (81380339) 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, 1312554 + ... + 1312615.

It is an arithmetic number, because the mean of its divisors is an integer number (21001360).

Almost surely, 2^81380239 is an apocalyptic number.

81380239 is a deficient number, since it is larger than the sum of its proper divisors (2625201).

81380239 is a wasteful number, since it uses less digits than its factorization.

81380239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2625200.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 81380239 is about 9021.0996558069. The cubic root of 81380239 is about 433.3508509026.

The spelling of 81380239 in words is "eighty-one million, three hundred eighty thousand, two hundred thirty-nine".