21238217 has 32 divisors (see below), whose sum is σ = 29164800. Its totient is φ = 15240960.

The previous prime is 21238211. The next prime is 21238229. The reversal of 21238217 is 71283212.

It is not a de Polignac number, because 21238217 - 2²⁰ = 20189641 is a prime.

It is a super-2 number, since 2×21238217² = 902123722678178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21238211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48833 + ... + 49265.

It is an arithmetic number, because the mean of its divisors is an integer number (911400).

Almost surely, 2^21238217 is an apocalyptic number.

It is an amenable number.

21238217 is a deficient number, since it is larger than the sum of its proper divisors (7926583).

21238217 is a wasteful number, since it uses less digits than its factorization.

21238217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478 (or 464 counting only the distinct ones).

The product of its digits is 1344, while the sum is 26.

The square root of 21238217 is about 4608.4940056379. The cubic root of 21238217 is about 276.9317082404.

The spelling of 21238217 in words is "twenty-one million, two hundred thirty-eight thousand, two hundred seventeen".