21213320237 has 2 divisors, whose sum is σ = 21213320238. Its totient is φ = 21213320236.

The previous prime is 21213320221. The next prime is 21213320291. The reversal of 21213320237 is 73202331212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20718435721 + 494884516 = 143939^2 + 22246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213320237 - 2⁴ = 21213320221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213320537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606660118 + 10606660119.

It is an arithmetic number, because the mean of its divisors is an integer number (10606660119).

Almost surely, 2^21213320237 is an apocalyptic number.

It is an amenable number.

21213320237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213320237 is an equidigital number, since it uses as much as digits as its factorization.

21213320237 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 26.

Adding to 21213320237 its reverse (73202331212), we get a palindrome (94415651449).

The spelling of 21213320237 in words is "twenty-one billion, two hundred thirteen million, three hundred twenty thousand, two hundred thirty-seven".