21440164 has 12 divisors (see below), whose sum is σ = 38814300. Its totient is φ = 10350368.

The previous prime is 21440149. The next prime is 21440183. The reversal of 21440164 is 46104412.

It can be written as a sum of positive squares in 2 ways, for example, as 16564900 + 4875264 = 4070^2 + 2208^2 .

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, 92299 + ... + 92530.

It is an arithmetic number, because the mean of its divisors is an integer number (3234525).

Almost surely, 2^21440164 is an apocalyptic number.

It is an amenable number.

21440164 is a deficient number, since it is larger than the sum of its proper divisors (17374136).

21440164 is a wasteful number, since it uses less digits than its factorization.

21440164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184862 (or 184860 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21440164 is about 4630.3524703849. The cubic root of 21440164 is about 277.8066906556.

Adding to 21440164 its reverse (46104412), we get a palindrome (67544576).

The spelling of 21440164 in words is "twenty-one million, four hundred forty thousand, one hundred sixty-four".