21123533 has 2 divisors, whose sum is σ = 21123534. Its totient is φ = 21123532.

The previous prime is 21123523. The next prime is 21123589. The reversal of 21123533 is 33532112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19386409 + 1737124 = 4403^2 + 1318^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123533 - 2⁴ = 21123517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561766 + 10561767.

It is an arithmetic number, because the mean of its divisors is an integer number (10561767).

Almost surely, 2^21123533 is an apocalyptic number.

It is an amenable number.

21123533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123533 is an equidigital number, since it uses as much as digits as its factorization.

21123533 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 540, while the sum is 20.

The square root of 21123533 is about 4596.0344863806. The cubic root of 21123533 is about 276.4323415515.

Adding to 21123533 its reverse (33532112), we get a palindrome (54655645).

The spelling of 21123533 in words is "twenty-one million, one hundred twenty-three thousand, five hundred thirty-three".