21113251 has 2 divisors, whose sum is σ = 21113252. Its totient is φ = 21113250.

The previous prime is 21113243. The next prime is 21113297. The reversal of 21113251 is 15231112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21113251 - 2³ = 21113243 is a prime.

It is not a weakly prime, because it can be changed into another prime (21113221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556625 + 10556626.

It is an arithmetic number, because the mean of its divisors is an integer number (10556626).

Almost surely, 2^21113251 is an apocalyptic number.

21113251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113251 is an equidigital number, since it uses as much as digits as its factorization.

21113251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60, while the sum is 16.

The square root of 21113251 is about 4594.9157772477. The cubic root of 21113251 is about 276.3874826000.

Adding to 21113251 its reverse (15231112), we get a palindrome (36344363).

The spelling of 21113251 in words is "twenty-one million, one hundred thirteen thousand, two hundred fifty-one".