21268917 has 6 divisors (see below), whose sum is σ = 30721782. Its totient is φ = 14179272.

The previous prime is 21268909. The next prime is 21268927. The reversal of 21268917 is 71986212.

It can be written as a sum of positive squares in only one way, i.e., 19000881 + 2268036 = 4359^2 + 1506^2 .

It is not a de Polignac number, because 21268917 - 2³ = 21268909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21268927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1181598 + ... + 1181615.

It is an arithmetic number, because the mean of its divisors is an integer number (5120297).

Almost surely, 2^21268917 is an apocalyptic number.

It is an amenable number.

21268917 is a deficient number, since it is larger than the sum of its proper divisors (9452865).

21268917 is a wasteful number, since it uses less digits than its factorization.

21268917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2363219 (or 2363216 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21268917 is about 4611.8236089426. The cubic root of 21268917 is about 277.0650796098.

The spelling of 21268917 in words is "twenty-one million, two hundred sixty-eight thousand, nine hundred seventeen".