21664299 has 8 divisors (see below), whose sum is σ = 29166592. Its totient is φ = 14302440.

The previous prime is 21664297. The next prime is 21664327. The reversal of 21664299 is 99246612.

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

It is not a de Polignac number, because 21664299 - 2¹ = 21664297 is a prime.

It is a super-2 number, since 2×21664299² = 938683702322802, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21664297) 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 7 ways as a sum of consecutive naturals, for example, 34747 + ... + 35364.

It is an arithmetic number, because the mean of its divisors is an integer number (3645824).

Almost surely, 2^21664299 is an apocalyptic number.

21664299 is a deficient number, since it is larger than the sum of its proper divisors (7502293).

21664299 is a wasteful number, since it uses less digits than its factorization.

21664299 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70217.

The product of its digits is 46656, while the sum is 39.

The square root of 21664299 is about 4654.4923461104. The cubic root of 21664299 is about 278.7713984123.

The spelling of 21664299 in words is "twenty-one million, six hundred sixty-four thousand, two hundred ninety-nine".