81667783 has 4 divisors (see below), whose sum is σ = 81712008. Its totient is φ = 81623560.

The previous prime is 81667771. The next prime is 81667823. The reversal of 81667783 is 38776618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38776618 = 2 ⋅19388309.

It is a cyclic number.

It is not a de Polignac number, because 81667783 - 2¹⁷ = 81536711 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 (81667763) 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, 19216 + ... + 23077.

It is an arithmetic number, because the mean of its divisors is an integer number (20428002).

Almost surely, 2^81667783 is an apocalyptic number.

81667783 is a deficient number, since it is larger than the sum of its proper divisors (44225).

81667783 is a wasteful number, since it uses less digits than its factorization.

81667783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44224.

The product of its digits is 338688, while the sum is 46.

The square root of 81667783 is about 9037.0229058026. The cubic root of 81667783 is about 433.8606428205.

The spelling of 81667783 in words is "eighty-one million, six hundred sixty-seven thousand, seven hundred eighty-three".