81992911 has 32 divisors (see below), whose sum is σ = 111315456. Its totient is φ = 58320000.

The previous prime is 81992909. The next prime is 81992927. The reversal of 81992911 is 11929918.

It is a 7-Lehmer number, since φ(81992911) divides (81992911-1)⁷.

It is a cyclic number.

It is not a de Polignac number, because 81992911 - 2¹ = 81992909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81992951) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 100696 + ... + 101506.

It is an arithmetic number, because the mean of its divisors is an integer number (3478608).

It is a vampire number, since it can be written as 8921 ⋅ 9191 (with its own digits).

Almost surely, 2^81992911 is an apocalyptic number.

81992911 is a deficient number, since it is larger than the sum of its proper divisors (29322545).

81992911 is a wasteful number, since it uses less digits than its factorization.

81992911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 943.

The product of its digits is 11664, while the sum is 40.

The square root of 81992911 is about 9054.9937051331. The cubic root of 81992911 is about 434.4356286920.

The spelling of 81992911 in words is "eighty-one million, nine hundred ninety-two thousand, nine hundred eleven".