21120031421 has 2 divisors, whose sum is σ = 21120031422. Its totient is φ = 21120031420.

The previous prime is 21120031393. The next prime is 21120031423. The reversal of 21120031421 is 12413002112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11630544025 + 9489487396 = 107845^2 + 97414^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120031421 - 2¹⁰ = 21120030397 is a prime.

Together with 21120031423, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21120031421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120031423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560015710 + 10560015711.

It is an arithmetic number, because the mean of its divisors is an integer number (10560015711).

Almost surely, 2^21120031421 is an apocalyptic number.

It is an amenable number.

21120031421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120031421 is an equidigital number, since it uses as much as digits as its factorization.

21120031421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21120031421 its reverse (12413002112), we get a palindrome (33533033533).

The spelling of 21120031421 in words is "twenty-one billion, one hundred twenty million, thirty-one thousand, four hundred twenty-one".