21766117 has 4 divisors (see below), whose sum is σ = 21783916. Its totient is φ = 21748320.

The previous prime is 21766099. The next prime is 21766139. The reversal of 21766117 is 71166712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14508481 + 7257636 = 3809^2 + 2694^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21766117 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 (21746117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6918 + ... + 9559.

It is an arithmetic number, because the mean of its divisors is an integer number (5445979).

Almost surely, 2^21766117 is an apocalyptic number.

It is an amenable number.

21766117 is a deficient number, since it is larger than the sum of its proper divisors (17799).

21766117 is a wasteful number, since it uses less digits than its factorization.

21766117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17798.

The product of its digits is 3528, while the sum is 31.

The square root of 21766117 is about 4665.4171303325. The cubic root of 21766117 is about 279.2074398406.

The spelling of 21766117 in words is "twenty-one million, seven hundred sixty-six thousand, one hundred seventeen".