21664322 has 4 divisors (see below), whose sum is σ = 32496486. Its totient is φ = 10832160.

The previous prime is 21664297. The next prime is 21664327. The reversal of 21664322 is 22346612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 15217801 + 6446521 = 3901^2 + 2539^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21664291 and 21664300.

It is not an unprimeable number, because it can be changed into a prime (21664327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5416079 + ... + 5416082.

Almost surely, 2^21664322 is an apocalyptic number.

21664322 is a deficient number, since it is larger than the sum of its proper divisors (10832164).

21664322 is a wasteful number, since it uses less digits than its factorization.

21664322 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10832163.

The product of its digits is 3456, while the sum is 26.

The square root of 21664322 is about 4654.4948168410. The cubic root of 21664322 is about 278.7714970652.

The spelling of 21664322 in words is "twenty-one million, six hundred sixty-four thousand, three hundred twenty-two".