21679417 has 4 divisors (see below), whose sum is σ = 21953920. Its totient is φ = 21404916.

The previous prime is 21679397. The next prime is 21679429. The reversal of 21679417 is 71497612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21679417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21679457) 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 3 ways as a sum of consecutive naturals, for example, 137133 + ... + 137290.

It is an arithmetic number, because the mean of its divisors is an integer number (5488480).

Almost surely, 2^21679417 is an apocalyptic number.

It is an amenable number.

21679417 is a deficient number, since it is larger than the sum of its proper divisors (274503).

21679417 is an equidigital number, since it uses as much as digits as its factorization.

21679417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274502.

The product of its digits is 21168, while the sum is 37.

The square root of 21679417 is about 4656.1160853226. The cubic root of 21679417 is about 278.8362283590.

It can be divided in two parts, 216794 and 17, that added together give a triangular number (216811 = T₆₅₈).

The spelling of 21679417 in words is "twenty-one million, six hundred seventy-nine thousand, four hundred seventeen".