21001122251 has 2 divisors, whose sum is σ = 21001122252. Its totient is φ = 21001122250.

The previous prime is 21001122229. The next prime is 21001122269. The reversal of 21001122251 is 15222110012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21001122251 - 2¹⁸ = 21000860107 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001122271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500561125 + 10500561126.

It is an arithmetic number, because the mean of its divisors is an integer number (10500561126).

Almost surely, 2^21001122251 is an apocalyptic number.

21001122251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001122251 is an equidigital number, since it uses as much as digits as its factorization.

21001122251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80, while the sum is 17.

Adding to 21001122251 its reverse (15222110012), we get a palindrome (36223232263).

The spelling of 21001122251 in words is "twenty-one billion, one million, one hundred twenty-two thousand, two hundred fifty-one".