21251611 has 2 divisors, whose sum is σ = 21251612. Its totient is φ = 21251610.

The previous prime is 21251599. The next prime is 21251617. The reversal of 21251611 is 11615212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21251611 - 2⁹ = 21251099 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21251617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625805 + 10625806.

It is an arithmetic number, because the mean of its divisors is an integer number (10625806).

Almost surely, 2^21251611 is an apocalyptic number.

21251611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251611 is an equidigital number, since it uses as much as digits as its factorization.

21251611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120, while the sum is 19.

The square root of 21251611 is about 4609.9469628186. The cubic root of 21251611 is about 276.9899121820.

Adding to 21251611 its reverse (11615212), we get a palindrome (32866823).

The spelling of 21251611 in words is "twenty-one million, two hundred fifty-one thousand, six hundred eleven".