21144623 has 2 divisors, whose sum is σ = 21144624. Its totient is φ = 21144622.

The previous prime is 21144619. The next prime is 21144631. The reversal of 21144623 is 32644112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21144623 - 2² = 21144619 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21144223) 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, 10572311 + 10572312.

It is an arithmetic number, because the mean of its divisors is an integer number (10572312).

Almost surely, 2^21144623 is an apocalyptic number.

21144623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144623 is an equidigital number, since it uses as much as digits as its factorization.

21144623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 23.

The square root of 21144623 is about 4598.3282831916. The cubic root of 21144623 is about 276.5243087889.

Adding to 21144623 its reverse (32644112), we get a palindrome (53788735).

The spelling of 21144623 in words is "twenty-one million, one hundred forty-four thousand, six hundred twenty-three".