21255653 has 2 divisors, whose sum is σ = 21255654. Its totient is φ = 21255652.

The previous prime is 21255613. The next prime is 21255673. The reversal of 21255653 is 35655212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12623809 + 8631844 = 3553^2 + 2938^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255653 - 2¹⁴ = 21239269 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627826 + 10627827.

It is an arithmetic number, because the mean of its divisors is an integer number (10627827).

Almost surely, 2^21255653 is an apocalyptic number.

It is an amenable number.

21255653 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255653 is an equidigital number, since it uses as much as digits as its factorization.

21255653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 29.

The square root of 21255653 is about 4610.3853418125. The cubic root of 21255653 is about 277.0074719841.

The spelling of 21255653 in words is "twenty-one million, two hundred fifty-five thousand, six hundred fifty-three".