81292447 has 4 divisors (see below), whose sum is σ = 83914816. Its totient is φ = 78670080.

The previous prime is 81292439. The next prime is 81292483. The reversal of 81292447 is 74429218.

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 81292447 - 2³ = 81292439 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 (81296447) 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, 1311138 + ... + 1311199.

It is an arithmetic number, because the mean of its divisors is an integer number (20978704).

Almost surely, 2^81292447 is an apocalyptic number.

81292447 is a deficient number, since it is larger than the sum of its proper divisors (2622369).

81292447 is a wasteful number, since it uses less digits than its factorization.

81292447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2622368.

The product of its digits is 32256, while the sum is 37.

The square root of 81292447 is about 9016.2324171463. The cubic root of 81292447 is about 433.1949636450.

The spelling of 81292447 in words is "eighty-one million, two hundred ninety-two thousand, four hundred forty-seven".