21213331421 has 2 divisors, whose sum is σ = 21213331422. Its totient is φ = 21213331420.

The previous prime is 21213331417. The next prime is 21213331441. The reversal of 21213331421 is 12413331212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12451435396 + 8761896025 = 111586^2 + 93605^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213331421 - 2² = 21213331417 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213331441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606665710 + 10606665711.

It is an arithmetic number, because the mean of its divisors is an integer number (10606665711).

Almost surely, 2^21213331421 is an apocalyptic number.

It is an amenable number.

21213331421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213331421 is an equidigital number, since it uses as much as digits as its factorization.

21213331421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 23.

Adding to 21213331421 its reverse (12413331212), we get a palindrome (33626662633).

The spelling of 21213331421 in words is "twenty-one billion, two hundred thirteen million, three hundred thirty-one thousand, four hundred twenty-one".