81517869 has 48 divisors (see below), whose sum is σ = 127370880. Its totient is φ = 50144640.

The previous prime is 81517841. The next prime is 81517901. The reversal of 81517869 is 96871518.

It is not a de Polignac number, because 81517869 - 2⁷ = 81517741 is a prime.

It is a super-2 number, since 2×81517869² = 13290325932602322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81517369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 982102 + ... + 982184.

It is an arithmetic number, because the mean of its divisors is an integer number (2653560).

Almost surely, 2^81517869 is an apocalyptic number.

It is an amenable number.

81517869 is a deficient number, since it is larger than the sum of its proper divisors (45853011).

81517869 is a wasteful number, since it uses less digits than its factorization.

81517869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242 (or 239 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 81517869 is about 9028.7246607702. The cubic root of 81517869 is about 433.5950071734.

The spelling of 81517869 in words is "eighty-one million, five hundred seventeen thousand, eight hundred sixty-nine".