81100609409 has 4 divisors (see below), whose sum is σ = 81208600320. Its totient is φ = 80992618500.

The previous prime is 81100609399. The next prime is 81100609417. The reversal of 81100609409 is 90490600118.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90490600118 = 2 ⋅45245300059.

It is a cyclic number.

It is not a de Polignac number, because 81100609409 - 2²⁸ = 80832173953 is a prime.

It is a super-2 number, since 2×81100609409² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81100602409) 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, 53994329 + ... + 53995830.

It is an arithmetic number, because the mean of its divisors is an integer number (20302150080).

Almost surely, 2^81100609409 is an apocalyptic number.

It is an amenable number.

81100609409 is a deficient number, since it is larger than the sum of its proper divisors (107990911).

81100609409 is a wasteful number, since it uses less digits than its factorization.

81100609409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107990910.

The product of its (nonzero) digits is 15552, while the sum is 38.

The spelling of 81100609409 in words is "eighty-one billion, one hundred million, six hundred nine thousand, four hundred nine".