2138823722921 has 2 divisors, whose sum is σ = 2138823722922. Its totient is φ = 2138823722920.

The previous prime is 2138823722863. The next prime is 2138823722929. The reversal of 2138823722921 is 1292273288312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2095939525696 + 42884197225 = 1447736^2 + 207085^2 .

It is a cyclic number.

It is not a de Polignac number, because 2138823722921 - 2¹⁸ = 2138823460777 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2138823722921.

It is not a weakly prime, because it can be changed into another prime (2138823722929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1069411861460 + 1069411861461.

It is an arithmetic number, because the mean of its divisors is an integer number (1069411861461).

Almost surely, 2^{2138823722921} is an apocalyptic number.

It is an amenable number.

2138823722921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2138823722921 is an equidigital number, since it uses as much as digits as its factorization.

2138823722921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1161216, while the sum is 50.

The spelling of 2138823722921 in words is "two trillion, one hundred thirty-eight billion, eight hundred twenty-three million, seven hundred twenty-two thousand, nine hundred twenty-one".