21140420251 has 2 divisors, whose sum is σ = 21140420252. Its totient is φ = 21140420250.

The previous prime is 21140420239. The next prime is 21140420299. The reversal of 21140420251 is 15202404112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21140420251 - 2⁵ = 21140420219 is a prime.

It is not a weakly prime, because it can be changed into another prime (21140420201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10570210125 + 10570210126.

It is an arithmetic number, because the mean of its divisors is an integer number (10570210126).

Almost surely, 2^21140420251 is an apocalyptic number.

21140420251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21140420251 is an equidigital number, since it uses as much as digits as its factorization.

21140420251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 22.

Adding to 21140420251 its reverse (15202404112), we get a palindrome (36342824363).

The spelling of 21140420251 in words is "twenty-one billion, one hundred forty million, four hundred twenty thousand, two hundred fifty-one".