21133664 has 24 divisors (see below), whose sum is σ = 41777568. Its totient is φ = 10523520.

The previous prime is 21133649. The next prime is 21133667. The reversal of 21133664 is 46633112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7454 + ... + 9890.

It is an arithmetic number, because the mean of its divisors is an integer number (1740732).

Almost surely, 2^21133664 is an apocalyptic number.

It is an amenable number.

21133664 is a deficient number, since it is larger than the sum of its proper divisors (20643904).

21133664 is a wasteful number, since it uses less digits than its factorization.

21133664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2718 (or 2710 counting only the distinct ones).

The product of its digits is 2592, while the sum is 26.

The square root of 21133664 is about 4597.1365000400. The cubic root of 21133664 is about 276.4765274752.

Adding to 21133664 its reverse (46633112), we get a palindrome (67766776).

The spelling of 21133664 in words is "twenty-one million, one hundred thirty-three thousand, six hundred sixty-four".