81785089 has 4 divisors (see below), whose sum is σ = 81803200. Its totient is φ = 81766980.

The previous prime is 81785071. The next prime is 81785111. The reversal of 81785089 is 98058718.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 98058718 = 2 ⋅49029359.

It is a cyclic number.

It is not a de Polignac number, because 81785089 - 2⁷ = 81784961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81785069) 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, 3844 + ... + 13354.

It is an arithmetic number, because the mean of its divisors is an integer number (20450800).

Almost surely, 2^81785089 is an apocalyptic number.

It is an amenable number.

81785089 is a deficient number, since it is larger than the sum of its proper divisors (18111).

81785089 is an equidigital number, since it uses as much as digits as its factorization.

81785089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18110.

The product of its (nonzero) digits is 161280, while the sum is 46.

The square root of 81785089 is about 9043.5108779721. The cubic root of 81785089 is about 434.0682730765.

The spelling of 81785089 in words is "eighty-one million, seven hundred eighty-five thousand, eighty-nine".