21031617 has 8 divisors (see below), whose sum is σ = 28397440. Its totient is φ = 13843440.

The previous prime is 21031559. The next prime is 21031627. The reversal of 21031617 is 71613012.

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

It is not a de Polignac number, because 21031617 - 2¹⁶ = 20966081 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031593 and 21031602.

It is not an unprimeable number, because it can be changed into a prime (21031627) 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, 44134 + ... + 44607.

It is an arithmetic number, because the mean of its divisors is an integer number (3549680).

Almost surely, 2^21031617 is an apocalyptic number.

It is an amenable number.

21031617 is a deficient number, since it is larger than the sum of its proper divisors (7365823).

21031617 is an equidigital number, since it uses as much as digits as its factorization.

21031617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88823.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 21031617 is about 4586.0240950087. The cubic root of 21031617 is about 276.0308067902.

Adding to 21031617 its reverse (71613012), we get a palindrome (92644629).

The spelling of 21031617 in words is "twenty-one million, thirty-one thousand, six hundred seventeen".