21868917 has 16 divisors (see below), whose sum is σ = 33423360. Its totient is φ = 12459312.

The previous prime is 21868909. The next prime is 21868921. The reversal of 21868917 is 71986812.

It is not a de Polignac number, because 21868917 - 2³ = 21868909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868937) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6684 + ... + 9402.

It is an arithmetic number, because the mean of its divisors is an integer number (2088960).

Almost surely, 2^21868917 is an apocalyptic number.

It is an amenable number.

21868917 is a deficient number, since it is larger than the sum of its proper divisors (11554443).

21868917 is a wasteful number, since it uses less digits than its factorization.

21868917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3112.

The product of its digits is 48384, while the sum is 42.

The square root of 21868917 is about 4676.4213881985. The cubic root of 21868917 is about 279.6463093653.

The spelling of 21868917 in words is "twenty-one million, eight hundred sixty-eight thousand, nine hundred seventeen".