21742617 has 16 divisors (see below), whose sum is σ = 31619840. Its totient is φ = 13208832.

The previous prime is 21742603. The next prime is 21742619. The reversal of 21742617 is 71624712.

It is not a de Polignac number, because 21742617 - 2¹⁰ = 21741593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21742619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 448 + ... + 6609.

It is an arithmetic number, because the mean of its divisors is an integer number (1976240).

Almost surely, 2^21742617 is an apocalyptic number.

It is an amenable number.

21742617 is a deficient number, since it is larger than the sum of its proper divisors (9877223).

21742617 is a wasteful number, since it uses less digits than its factorization.

21742617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7152.

The product of its digits is 4704, while the sum is 30.

The square root of 21742617 is about 4662.8979186768. The cubic root of 21742617 is about 279.1069206467.

The spelling of 21742617 in words is "twenty-one million, seven hundred forty-two thousand, six hundred seventeen".