21050251 has 2 divisors, whose sum is σ = 21050252. Its totient is φ = 21050250.

The previous prime is 21050231. The next prime is 21050269. The reversal of 21050251 is 15205012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21050251 - 2¹³ = 21042059 is a prime.

It is a super-2 number, since 2×21050251² = 886226134326002, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21050231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525125 + 10525126.

It is an arithmetic number, because the mean of its divisors is an integer number (10525126).

Almost surely, 2^21050251 is an apocalyptic number.

21050251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21050251 is an equidigital number, since it uses as much as digits as its factorization.

21050251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21050251 is about 4588.0552525008. The cubic root of 21050251 is about 276.1123037691.

Adding to 21050251 its reverse (15205012), we get a palindrome (36255263).

The spelling of 21050251 in words is "twenty-one million, fifty thousand, two hundred fifty-one".