21661117 has 4 divisors (see below), whose sum is σ = 21673600. Its totient is φ = 21648636.

The previous prime is 21661109. The next prime is 21661141. The reversal of 21661117 is 71116612.

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 a cyclic number.

It is not a de Polignac number, because 21661117 - 2³ = 21661109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21661091 and 21661100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661517) 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, 3117 + ... + 7282.

It is an arithmetic number, because the mean of its divisors is an integer number (5418400).

Almost surely, 2^21661117 is an apocalyptic number.

It is an amenable number.

21661117 is a deficient number, since it is larger than the sum of its proper divisors (12483).

21661117 is a wasteful number, since it uses less digits than its factorization.

21661117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12482.

The product of its digits is 504, while the sum is 25.

The square root of 21661117 is about 4654.1505132516. The cubic root of 21661117 is about 278.7577493204.

Adding to 21661117 its reverse (71116612), we get a palindrome (92777729).

The spelling of 21661117 in words is "twenty-one million, six hundred sixty-one thousand, one hundred seventeen".