21002917 has 8 divisors (see below), whose sum is σ = 22708224. Its totient is φ = 19310448.

The previous prime is 21002911. The next prime is 21002921. The reversal of 21002917 is 71920012.

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

It is a cyclic number.

It is not a de Polignac number, because 21002917 - 2⁷ = 21002789 is a prime.

It is a super-2 number, since 2×21002917² = 882245045017778, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002911) 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 7 ways as a sum of consecutive naturals, for example, 348 + ... + 6490.

It is an arithmetic number, because the mean of its divisors is an integer number (2838528).

Almost surely, 2^21002917 is an apocalyptic number.

It is an amenable number.

21002917 is a deficient number, since it is larger than the sum of its proper divisors (1705307).

21002917 is a wasteful number, since it uses less digits than its factorization.

21002917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6419.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21002917 is about 4582.8939546972. The cubic root of 21002917 is about 275.9051913036.

Adding to 21002917 its reverse (71920012), we get a palindrome (92922929).

The spelling of 21002917 in words is "twenty-one million, two thousand, nine hundred seventeen".