21717427 has 8 divisors (see below), whose sum is σ = 22249136. Its totient is φ = 21192192.

The previous prime is 21717407. The next prime is 21717461. The reversal of 21717427 is 72471712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21717427 - 2¹⁵ = 21684659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21717407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5548 + ... + 8614.

It is an arithmetic number, because the mean of its divisors is an integer number (2781142).

Almost surely, 2^21717427 is an apocalyptic number.

21717427 is a deficient number, since it is larger than the sum of its proper divisors (531709).

21717427 is an equidigital number, since it uses as much as digits as its factorization.

21717427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3237.

The product of its digits is 5488, while the sum is 31.

The square root of 21717427 is about 4660.1960259199. The cubic root of 21717427 is about 278.9990921636. Note that the first 3 decimals are identical.

The spelling of 21717427 in words is "twenty-one million, seven hundred seventeen thousand, four hundred twenty-seven".