21427917 has 16 divisors (see below), whose sum is σ = 32727552. Its totient is φ = 12216240.

The previous prime is 21427891. The next prime is 21427943. The reversal of 21427917 is 71972412.

It is an interprime number because it is at equal distance from previous prime (21427891) and next prime (21427943).

It is not a de Polignac number, because 21427917 - 2⁶ = 21427853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427997) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11098 + ... + 12884.

It is an arithmetic number, because the mean of its divisors is an integer number (2045472).

Almost surely, 2^21427917 is an apocalyptic number.

It is an amenable number.

21427917 is a deficient number, since it is larger than the sum of its proper divisors (11299635).

21427917 is a wasteful number, since it uses less digits than its factorization.

21427917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2368.

The product of its digits is 7056, while the sum is 33.

The square root of 21427917 is about 4629.0298119584. The cubic root of 21427917 is about 277.7537845528.

The spelling of 21427917 in words is "twenty-one million, four hundred twenty-seven thousand, nine hundred seventeen".