21253711 has 2 divisors, whose sum is σ = 21253712. Its totient is φ = 21253710.

The previous prime is 21253697. The next prime is 21253721. The reversal of 21253711 is 11735212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21253711 - 2¹³ = 21245519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21253721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626855 + 10626856.

It is an arithmetic number, because the mean of its divisors is an integer number (10626856).

Almost surely, 2^21253711 is an apocalyptic number.

21253711 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253711 is an equidigital number, since it uses as much as digits as its factorization.

21253711 is an evil number, because the sum of its binary digits is even.

The product of its digits is 420, while the sum is 22.

The square root of 21253711 is about 4610.1747255392. The cubic root of 21253711 is about 276.9990355634. Note that the first 3 decimals are identical.

Adding to 21253711 its reverse (11735212), we get a palindrome (32988923).

The spelling of 21253711 in words is "twenty-one million, two hundred fifty-three thousand, seven hundred eleven".