81784943 has 4 divisors (see below), whose sum is σ = 86595840. Its totient is φ = 76974048.

The previous prime is 81784933. The next prime is 81784951. The reversal of 81784943 is 34948718.

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 81784943 - 2²⁴ = 65007727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81784894 and 81784903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81784903) 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, 2405423 + ... + 2405456.

It is an arithmetic number, because the mean of its divisors is an integer number (21648960).

Almost surely, 2^81784943 is an apocalyptic number.

81784943 is a deficient number, since it is larger than the sum of its proper divisors (4810897).

81784943 is a wasteful number, since it uses less digits than its factorization.

81784943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4810896.

The product of its digits is 193536, while the sum is 44.

The square root of 81784943 is about 9043.5028058822. The cubic root of 81784943 is about 434.0680147816.

The spelling of 81784943 in words is "eighty-one million, seven hundred eighty-four thousand, nine hundred forty-three".