81707569 has 4 divisors (see below), whose sum is σ = 85260096. Its totient is φ = 78155044.

The previous prime is 81707557. The next prime is 81707579. The reversal of 81707569 is 96570718.

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.

It is a cyclic number.

It is not a de Polignac number, because 81707569 - 2¹⁷ = 81576497 is a prime.

It is a super-2 number, since 2×81707569² = 13352253663779522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81707519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1776229 + ... + 1776274.

It is an arithmetic number, because the mean of its divisors is an integer number (21315024).

Almost surely, 2^81707569 is an apocalyptic number.

It is an amenable number.

81707569 is a deficient number, since it is larger than the sum of its proper divisors (3552527).

81707569 is a wasteful number, since it uses less digits than its factorization.

81707569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3552526.

The product of its (nonzero) digits is 105840, while the sum is 43.

The square root of 81707569 is about 9039.2239158016. The cubic root of 81707569 is about 433.9310858462.

The spelling of 81707569 in words is "eighty-one million, seven hundred seven thousand, five hundred sixty-nine".