21617617 has 8 divisors (see below), whose sum is σ = 25075136. Its totient is φ = 18252432.

The previous prime is 21617581. The next prime is 21617621. The reversal of 21617617 is 71671612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21617617 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21617627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22578 + ... + 23515.

It is an arithmetic number, because the mean of its divisors is an integer number (3134392).

Almost surely, 2^21617617 is an apocalyptic number.

It is an amenable number.

21617617 is a deficient number, since it is larger than the sum of its proper divisors (3457519).

21617617 is an equidigital number, since it uses as much as digits as its factorization.

21617617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46167.

The product of its digits is 3528, while the sum is 31.

The square root of 21617617 is about 4649.4749165900. The cubic root of 21617617 is about 278.5710232110.

The spelling of 21617617 in words is "twenty-one million, six hundred seventeen thousand, six hundred seventeen".