21445623 has 24 divisors (see below), whose sum is σ = 33022080. Its totient is φ = 13372560.

The previous prime is 21445609. The next prime is 21445643. The reversal of 21445623 is 32654412.

It is not a de Polignac number, because 21445623 - 2⁹ = 21445111 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21445603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13438 + ... + 14948.

It is an arithmetic number, because the mean of its divisors is an integer number (1375920).

Almost surely, 2^21445623 is an apocalyptic number.

21445623 is a deficient number, since it is larger than the sum of its proper divisors (11576457).

21445623 is a wasteful number, since it uses less digits than its factorization.

21445623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1619 (or 1616 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21445623 is about 4630.9419128294. The cubic root of 21445623 is about 277.8302666263.

The spelling of 21445623 in words is "twenty-one million, four hundred forty-five thousand, six hundred twenty-three".