21646004 has 12 divisors (see below), whose sum is σ = 37922724. Its totient is φ = 10810944.

The previous prime is 21646003. The next prime is 21646021. The reversal of 21646004 is 40064612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6451600 + 15194404 = 2540^2 + 3898^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21646003) by changing a digit.

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, 1922 + ... + 6854.

It is an arithmetic number, because the mean of its divisors is an integer number (3160227).

Almost surely, 2^21646004 is an apocalyptic number.

It is an amenable number.

21646004 is a deficient number, since it is larger than the sum of its proper divisors (16276720).

21646004 is a wasteful number, since it uses less digits than its factorization.

21646004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6034 (or 6032 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21646004 is about 4652.5266253940. The cubic root of 21646004 is about 278.6929043108.

The spelling of 21646004 in words is "twenty-one million, six hundred forty-six thousand, four".