21007617 has 4 divisors (see below), whose sum is σ = 28010160. Its totient is φ = 14005076.

The previous prime is 21007589. The next prime is 21007627. The reversal of 21007617 is 71670012.

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 not a de Polignac number, because 21007617 - 2¹⁰ = 21006593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21007627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3501267 + ... + 3501272.

It is an arithmetic number, because the mean of its divisors is an integer number (7002540).

Almost surely, 2^21007617 is an apocalyptic number.

It is an amenable number.

21007617 is a deficient number, since it is larger than the sum of its proper divisors (7002543).

21007617 is an equidigital number, since it uses as much as digits as its factorization.

21007617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7002542.

The product of its (nonzero) digits is 588, while the sum is 24.

The square root of 21007617 is about 4583.4067024431. The cubic root of 21007617 is about 275.9257703130.

Adding to 21007617 its reverse (71670012), we get a palindrome (92677629).

The spelling of 21007617 in words is "twenty-one million, seven thousand, six hundred seventeen".