2181211721023 has 4 divisors (see below), whose sum is σ = 2181220067880. Its totient is φ = 2181203374168.

The previous prime is 2181211720969. The next prime is 2181211721027. The reversal of 2181211721023 is 3201271121812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2181211721023 - 2³³ = 2172621786431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181211721027) 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, 3768340 + ... + 4308457.

It is an arithmetic number, because the mean of its divisors is an integer number (545305016970).

Almost surely, 2^{2181211721023} is an apocalyptic number.

2181211721023 is a deficient number, since it is larger than the sum of its proper divisors (8346857).

2181211721023 is an equidigital number, since it uses as much as digits as its factorization.

2181211721023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8346856.

The product of its (nonzero) digits is 2688, while the sum is 31.

Adding to 2181211721023 its reverse (3201271121812), we get a palindrome (5382482842835).

The spelling of 2181211721023 in words is "two trillion, one hundred eighty-one billion, two hundred eleven million, seven hundred twenty-one thousand, twenty-three".