36666581921 has 4 divisors (see below), whose sum is σ = 36694637232. Its totient is φ = 36638526612.

The previous prime is 36666581893. The next prime is 36666581933. The reversal of 36666581921 is 12918566663.

It is a happy number.

36666581921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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: 12918566663 = 59 ⋅218958757.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-36666581921 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (36666586921) 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, 14025695 + ... + 14028308.

It is an arithmetic number, because the mean of its divisors is an integer number (9173659308).

Almost surely, 2^36666581921 is an apocalyptic number.

It is an amenable number.

36666581921 is a deficient number, since it is larger than the sum of its proper divisors (28055311).

36666581921 is a wasteful number, since it uses less digits than its factorization.

36666581921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28055310.

The product of its digits is 2799360, while the sum is 53.

The spelling of 36666581921 in words is "thirty-six billion, six hundred sixty-six million, five hundred eighty-one thousand, nine hundred twenty-one".