21632261 has 8 divisors (see below), whose sum is σ = 24978240. Its totient is φ = 18350208.

The previous prime is 21632257. The next prime is 21632287. The reversal of 21632261 is 16223612.

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 21632261 - 2² = 21632257 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21632201) 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, 15251 + ... + 16608.

It is an arithmetic number, because the mean of its divisors is an integer number (3122280).

Almost surely, 2^21632261 is an apocalyptic number.

It is an amenable number.

21632261 is a deficient number, since it is larger than the sum of its proper divisors (3345979).

21632261 is an equidigital number, since it uses as much as digits as its factorization.

21632261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31963.

The product of its digits is 864, while the sum is 23.

The square root of 21632261 is about 4651.0494514679. The cubic root of 21632261 is about 278.6339113216.

Adding to 21632261 its reverse (16223612), we get a palindrome (37855873).

The spelling of 21632261 in words is "twenty-one million, six hundred thirty-two thousand, two hundred sixty-one".