21626917 has 4 divisors (see below), whose sum is σ = 23290540. Its totient is φ = 19963296.

The previous prime is 21626887. The next prime is 21626951. The reversal of 21626917 is 71962612.

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 8767521 + 12859396 = 2961^2 + 3586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21626917 - 2¹⁵ = 21594149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21626977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 831792 + ... + 831817.

It is an arithmetic number, because the mean of its divisors is an integer number (5822635).

Almost surely, 2^21626917 is an apocalyptic number.

It is an amenable number.

21626917 is a deficient number, since it is larger than the sum of its proper divisors (1663623).

21626917 is a wasteful number, since it uses less digits than its factorization.

21626917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663622.

The product of its digits is 9072, while the sum is 34.

The square root of 21626917 is about 4650.4749219838. The cubic root of 21626917 is about 278.6109650031.

The spelling of 21626917 in words is "twenty-one million, six hundred twenty-six thousand, nine hundred seventeen".