21017117 has 16 divisors (see below), whose sum is σ = 24458112. Its totient is φ = 17848320.

The previous prime is 21017111. The next prime is 21017137. The reversal of 21017117 is 71171012.

It is a cyclic number.

It is not a de Polignac number, because 21017117 - 2¹² = 21013021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21017111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30893 + ... + 31565.

It is an arithmetic number, because the mean of its divisors is an integer number (1528632).

Almost surely, 2^21017117 is an apocalyptic number.

It is an amenable number.

21017117 is a deficient number, since it is larger than the sum of its proper divisors (3440995).

21017117 is a wasteful number, since it uses less digits than its factorization.

21017117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 868.

The product of its (nonzero) digits is 98, while the sum is 20.

The square root of 21017117 is about 4584.4429323529. The cubic root of 21017117 is about 275.9673568129.

Adding to 21017117 its reverse (71171012), we get a palindrome (92188129).

The spelling of 21017117 in words is "twenty-one million, seventeen thousand, one hundred seventeen".