81612105 has 16 divisors (see below), whose sum is σ = 131610624. Its totient is φ = 43182720.

The previous prime is 81612101. The next prime is 81612107. The reversal of 81612105 is 50121618.

It is not a de Polignac number, because 81612105 - 2² = 81612101 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81612101) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19516 + ... + 23325.

It is an arithmetic number, because the mean of its divisors is an integer number (8225664).

It is a Poulet number, since it divides 2^81612104-1.

Almost surely, 2^81612105 is an apocalyptic number.

It is an amenable number.

81612105 is a deficient number, since it is larger than the sum of its proper divisors (49998519).

81612105 is a wasteful number, since it uses less digits than its factorization.

81612105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42976.

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 81612105 is about 9033.9418306739. The cubic root of 81612105 is about 433.7620238232.

It can be divided in two parts, 816 and 12105, that added together give a palindrome (12921).

The spelling of 81612105 in words is "eighty-one million, six hundred twelve thousand, one hundred five".