21003455251 has 2 divisors, whose sum is σ = 21003455252. Its totient is φ = 21003455250.

The previous prime is 21003455243. The next prime is 21003455267. The reversal of 21003455251 is 15255430012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21003455251 - 2³ = 21003455243 is a prime.

It is a super-2 number, since 2×21003455251² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21000455251) 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, 10501727625 + 10501727626.

It is an arithmetic number, because the mean of its divisors is an integer number (10501727626).

Almost surely, 2^21003455251 is an apocalyptic number.

21003455251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003455251 is an equidigital number, since it uses as much as digits as its factorization.

21003455251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6000, while the sum is 28.

Adding to 21003455251 its reverse (15255430012), we get a palindrome (36258885263).

The spelling of 21003455251 in words is "twenty-one billion, three million, four hundred fifty-five thousand, two hundred fifty-one".