21210302251 has 2 divisors, whose sum is σ = 21210302252. Its totient is φ = 21210302250.

The previous prime is 21210302189. The next prime is 21210302279. The reversal of 21210302251 is 15220301212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21210302251 - 2¹¹ = 21210300203 is a prime.

It is not a weakly prime, because it can be changed into another prime (21210303251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605151125 + 10605151126.

It is an arithmetic number, because the mean of its divisors is an integer number (10605151126).

Almost surely, 2^21210302251 is an apocalyptic number.

21210302251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210302251 is an equidigital number, since it uses as much as digits as its factorization.

21210302251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21210302251 its reverse (15220301212), we get a palindrome (36430603463).

The spelling of 21210302251 in words is "twenty-one billion, two hundred ten million, three hundred two thousand, two hundred fifty-one".