21845864 has 16 divisors (see below), whose sum is σ = 41076420. Its totient is φ = 10892160.

The previous prime is 21845861. The next prime is 21845881. The reversal of 21845864 is 46854812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19096900 + 2748964 = 4370^2 + 1658^2 .

It is not an unprimeable number, because it can be changed into a prime (21845861) 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 in 3 ways as a sum of consecutive naturals, for example, 677 + ... + 6644.

Almost surely, 2^21845864 is an apocalyptic number.

It is an amenable number.

21845864 is a deficient number, since it is larger than the sum of its proper divisors (19230556).

21845864 is a wasteful number, since it uses less digits than its factorization.

21845864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7700 (or 7696 counting only the distinct ones).

The product of its digits is 61440, while the sum is 38.

The square root of 21845864 is about 4673.9559261936. The cubic root of 21845864 is about 279.5480122717.

The spelling of 21845864 in words is "twenty-one million, eight hundred forty-five thousand, eight hundred sixty-four".