21664735 has 8 divisors (see below), whose sum is σ = 27128160. Its totient is φ = 16578144.

The previous prime is 21664729. The next prime is 21664739. The reversal of 21664735 is 53746612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21664735 - 2⁵ = 21664703 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21664735.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664739) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 94080 + ... + 94309.

It is an arithmetic number, because the mean of its divisors is an integer number (3391020).

Almost surely, 2^21664735 is an apocalyptic number.

21664735 is a deficient number, since it is larger than the sum of its proper divisors (5463425).

21664735 is a wasteful number, since it uses less digits than its factorization.

21664735 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188417.

The product of its digits is 30240, while the sum is 34.

The square root of 21664735 is about 4654.5391823466. The cubic root of 21664735 is about 278.7732685168.

The spelling of 21664735 in words is "twenty-one million, six hundred sixty-four thousand, seven hundred thirty-five".