21645004 has 12 divisors (see below), whose sum is σ = 38685024. Its totient is φ = 10592144.

The previous prime is 21644969. The next prime is 21645023. The reversal of 21645004 is 40054612.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 57379 + ... + 57754.

It is an arithmetic number, because the mean of its divisors is an integer number (3223752).

Almost surely, 2^21645004 is an apocalyptic number.

It is an amenable number.

21645004 is a deficient number, since it is larger than the sum of its proper divisors (17040020).

21645004 is a wasteful number, since it uses less digits than its factorization.

21645004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115184 (or 115182 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21645004 is about 4652.4191556651. The cubic root of 21645004 is about 278.6886125687.

Adding to 21645004 its reverse (40054612), we get a palindrome (61699616).

The spelling of 21645004 in words is "twenty-one million, six hundred forty-five thousand, four".