21553111 has 2 divisors, whose sum is σ = 21553112. Its totient is φ = 21553110.

The previous prime is 21553099. The next prime is 21553123. The reversal of 21553111 is 11135512.

It is a balanced prime because it is at equal distance from previous prime (21553099) and next prime (21553123).

It is a cyclic number.

It is not a de Polignac number, because 21553111 - 2⁵ = 21553079 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21553141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776555 + 10776556.

It is an arithmetic number, because the mean of its divisors is an integer number (10776556).

Almost surely, 2^21553111 is an apocalyptic number.

21553111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21553111 is an equidigital number, since it uses as much as digits as its factorization.

21553111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 150, while the sum is 19.

The square root of 21553111 is about 4642.5328216395. The cubic root of 21553111 is about 278.2936660057.

Adding to 21553111 its reverse (11135512), we get a palindrome (32688623).

The spelling of 21553111 in words is "twenty-one million, five hundred fifty-three thousand, one hundred eleven".