81091101 has 48 divisors (see below), whose sum is σ = 136070016. Its totient is φ = 42052608.

The previous prime is 81091099. The next prime is 81091141. The reversal of 81091101 is 10119018.

It is not a de Polignac number, because 81091101 - 2¹ = 81091099 is a prime.

It is a super-2 number, since 2×81091101² = 13151533322784402, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81091141) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 258921 + ... + 259233.

It is an arithmetic number, because the mean of its divisors is an integer number (2834792).

Almost surely, 2^81091101 is an apocalyptic number.

It is an amenable number.

81091101 is a deficient number, since it is larger than the sum of its proper divisors (54978915).

81091101 is a wasteful number, since it uses less digits than its factorization.

81091101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422 (or 409 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 21.

The square root of 81091101 is about 9005.0597443882. The cubic root of 81091101 is about 432.8370206607.

The spelling of 81091101 in words is "eighty-one million, ninety-one thousand, one hundred one".