81994869 has 32 divisors (see below), whose sum is σ = 135043200. Its totient is φ = 48746880.

The previous prime is 81994867. The next prime is 81994877. The reversal of 81994869 is 96849918.

It is not a de Polignac number, because 81994869 - 2¹ = 81994867 is a prime.

It is a super-2 number, since 2×81994869² = 13446317084654322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81994867) 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 31 ways as a sum of consecutive naturals, for example, 13137 + ... + 18345.

It is an arithmetic number, because the mean of its divisors is an integer number (4220100).

Almost surely, 2^81994869 is an apocalyptic number.

It is an amenable number.

81994869 is a deficient number, since it is larger than the sum of its proper divisors (53048331).

81994869 is a wasteful number, since it uses less digits than its factorization.

81994869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5282 (or 5276 counting only the distinct ones).

The product of its digits is 1119744, while the sum is 54.

The square root of 81994869 is about 9055.1018216252. The cubic root of 81994869 is about 434.4390867885.

The spelling of 81994869 in words is "eighty-one million, nine hundred ninety-four thousand, eight hundred sixty-nine".