81101851 has 4 divisors (see below), whose sum is σ = 81252304. Its totient is φ = 80951400.

The previous prime is 81101843. The next prime is 81101869. The reversal of 81101851 is 15810118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15810118 = 2 ⋅7905059.

It is a cyclic number.

It is not a de Polignac number, because 81101851 - 2³ = 81101843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81101821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74415 + ... + 75496.

It is an arithmetic number, because the mean of its divisors is an integer number (20313076).

Almost surely, 2^81101851 is an apocalyptic number.

81101851 is a deficient number, since it is larger than the sum of its proper divisors (150453).

81101851 is a wasteful number, since it uses less digits than its factorization.

81101851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150452.

The product of its (nonzero) digits is 320, while the sum is 25.

The square root of 81101851 is about 9005.6566112638. The cubic root of 81101851 is about 432.8561464436.

Adding to 81101851 its reverse (15810118), we get a palindrome (96911969).

The spelling of 81101851 in words is "eighty-one million, one hundred one thousand, eight hundred fifty-one".