21126653 has 4 divisors (see below), whose sum is σ = 21173340. Its totient is φ = 21079968.

The previous prime is 21126649. The next prime is 21126671. The reversal of 21126653 is 35662112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20313049 + 813604 = 4507^2 + 902^2 .

It is a cyclic number.

It is not a de Polignac number, because 21126653 - 2² = 21126649 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21126643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22658 + ... + 23571.

It is an arithmetic number, because the mean of its divisors is an integer number (5293335).

Almost surely, 2^21126653 is an apocalyptic number.

It is an amenable number.

21126653 is a deficient number, since it is larger than the sum of its proper divisors (46687).

21126653 is an equidigital number, since it uses as much as digits as its factorization.

21126653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46686.

The product of its digits is 2160, while the sum is 26.

The square root of 21126653 is about 4596.3738968887. The cubic root of 21126653 is about 276.4459508034.

Adding to 21126653 its reverse (35662112), we get a palindrome (56788765).

The spelling of 21126653 in words is "twenty-one million, one hundred twenty-six thousand, six hundred fifty-three".