21261117 has 4 divisors (see below), whose sum is σ = 28348160. Its totient is φ = 14174076.

The previous prime is 21261113. The next prime is 21261127. The reversal of 21261117 is 71116212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21261117 - 2² = 21261113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21261093 and 21261102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261113) 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 3 ways as a sum of consecutive naturals, for example, 3543517 + ... + 3543522.

It is an arithmetic number, because the mean of its divisors is an integer number (7087040).

Almost surely, 2^21261117 is an apocalyptic number.

It is an amenable number.

21261117 is a deficient number, since it is larger than the sum of its proper divisors (7087043).

21261117 is an equidigital number, since it uses as much as digits as its factorization.

21261117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7087042.

The product of its digits is 168, while the sum is 21.

The square root of 21261117 is about 4610.9778789320. The cubic root of 21261117 is about 277.0312058923.

Adding to 21261117 its reverse (71116212), we get a palindrome (92377329).

The spelling of 21261117 in words is "twenty-one million, two hundred sixty-one thousand, one hundred seventeen".