21608213 has 8 divisors (see below), whose sum is σ = 23959776. Its totient is φ = 19321200.

The previous prime is 21608123. The next prime is 21608227. The reversal of 21608213 is 31280612.

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 21608213 - 2¹⁸ = 21346069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21608233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15431 + ... + 16772.

It is an arithmetic number, because the mean of its divisors is an integer number (2994972).

Almost surely, 2^21608213 is an apocalyptic number.

It is an amenable number.

21608213 is a deficient number, since it is larger than the sum of its proper divisors (2351563).

21608213 is a wasteful number, since it uses less digits than its factorization.

21608213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32275.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21608213 is about 4648.4635095911. The cubic root of 21608213 is about 278.5306231079.

Adding to 21608213 its reverse (31280612), we get a palindrome (52888825).

The spelling of 21608213 in words is "twenty-one million, six hundred eight thousand, two hundred thirteen".