21209241 has 8 divisors (see below), whose sum is σ = 28302624. Its totient is φ = 14127680.

The previous prime is 21209231. The next prime is 21209311. The reversal of 21209241 is 14290212.

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 21209241 - 2⁷ = 21209113 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21209231) 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, 2881 + ... + 7121.

It is an arithmetic number, because the mean of its divisors is an integer number (3537828).

Almost surely, 2^21209241 is an apocalyptic number.

It is an amenable number.

21209241 is a deficient number, since it is larger than the sum of its proper divisors (7093383).

21209241 is a wasteful number, since it uses less digits than its factorization.

21209241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5911.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21209241 is about 4605.3491724298. The cubic root of 21209241 is about 276.8057085664.

Adding to 21209241 its reverse (14290212), we get a palindrome (35499453).

The spelling of 21209241 in words is "twenty-one million, two hundred nine thousand, two hundred forty-one".