21624443 has 2 divisors, whose sum is σ = 21624444. Its totient is φ = 21624442.

The previous prime is 21624409. The next prime is 21624461. The reversal of 21624443 is 34442612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21624443 - 2¹⁰ = 21623419 is a prime.

It is not a weakly prime, because it can be changed into another prime (21624643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10812221 + 10812222.

It is an arithmetic number, because the mean of its divisors is an integer number (10812222).

Almost surely, 2^21624443 is an apocalyptic number.

21624443 is a deficient number, since it is larger than the sum of its proper divisors (1).

21624443 is an equidigital number, since it uses as much as digits as its factorization.

21624443 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 26.

The square root of 21624443 is about 4650.2089200379. The cubic root of 21624443 is about 278.6003407455.

The spelling of 21624443 in words is "twenty-one million, six hundred twenty-four thousand, four hundred forty-three".