21845387 has 2 divisors, whose sum is σ = 21845388. Its totient is φ = 21845386.

The previous prime is 21845353. The next prime is 21845401. The reversal of 21845387 is 78354812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21845387 - 2¹⁶ = 21779851 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21845387.

It is not a weakly prime, because it can be changed into another prime (21845287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922693 + 10922694.

It is an arithmetic number, because the mean of its divisors is an integer number (10922694).

Almost surely, 2^21845387 is an apocalyptic number.

21845387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845387 is an equidigital number, since it uses as much as digits as its factorization.

21845387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53760, while the sum is 38.

The square root of 21845387 is about 4673.9048984762. The cubic root of 21845387 is about 279.5459776322.

The spelling of 21845387 in words is "twenty-one million, eight hundred forty-five thousand, three hundred eighty-seven".