21268553 has 2 divisors, whose sum is σ = 21268554. Its totient is φ = 21268552.

The previous prime is 21268517. The next prime is 21268567. The reversal of 21268553 is 35586212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13935289 + 7333264 = 3733^2 + 2708^2 .

It is a cyclic number.

It is not a de Polignac number, because 21268553 - 2⁸ = 21268297 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21268153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10634276 + 10634277.

It is an arithmetic number, because the mean of its divisors is an integer number (10634277).

Almost surely, 2^21268553 is an apocalyptic number.

It is an amenable number.

21268553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21268553 is an equidigital number, since it uses as much as digits as its factorization.

21268553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 32.

The square root of 21268553 is about 4611.7841449920. The cubic root of 21268553 is about 277.0634990206.

The spelling of 21268553 in words is "twenty-one million, two hundred sixty-eight thousand, five hundred fifty-three".