21217814 has 4 divisors (see below), whose sum is σ = 31826724. Its totient is φ = 10608906.

The previous prime is 21217747. The next prime is 21217829. The reversal of 21217814 is 41871212.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5304452 + ... + 5304455.

It is an arithmetic number, because the mean of its divisors is an integer number (7956681).

Almost surely, 2^21217814 is an apocalyptic number.

21217814 is a deficient number, since it is larger than the sum of its proper divisors (10608910).

21217814 is a wasteful number, since it uses less digits than its factorization.

21217814 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10608909.

The product of its digits is 896, while the sum is 26.

The square root of 21217814 is about 4606.2798438653. The cubic root of 21217814 is about 276.8429994761.

The spelling of 21217814 in words is "twenty-one million, two hundred seventeen thousand, eight hundred fourteen".