81387969 has 16 divisors (see below), whose sum is σ = 118784064. Its totient is φ = 49262400.

The previous prime is 81387937. The next prime is 81387983. The reversal of 81387969 is 96978318.

It is not a de Polignac number, because 81387969 - 2⁵ = 81387937 is a prime.

It is a super-2 number, since 2×81387969² = 13248002995889922, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81387269) 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 15 ways as a sum of consecutive naturals, for example, 14727 + ... + 19484.

It is an arithmetic number, because the mean of its divisors is an integer number (7424004).

Almost surely, 2^81387969 is an apocalyptic number.

It is an amenable number.

81387969 is a deficient number, since it is larger than the sum of its proper divisors (37396095).

81387969 is a wasteful number, since it uses less digits than its factorization.

81387969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34288.

The product of its digits is 653184, while the sum is 51.

The square root of 81387969 is about 9021.5280856405. The cubic root of 81387969 is about 433.3645712524.

The spelling of 81387969 in words is "eighty-one million, three hundred eighty-seven thousand, nine hundred sixty-nine".