21417 has 12 divisors (see below), whose sum is σ = 31920. Its totient is φ = 12760.

The previous prime is 21407. The next prime is 21419. The reversal of 21417 is 71412.

It is not a de Polignac number, because 21417 - 2⁴ = 21401 is a prime.

It is a d-powerful number, because it can be written as 2⁹ + 1 + 4⁶ + 1 + 7⁵ .

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 21396 and 21405.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21417.

It is not an unprimeable number, because it can be changed into a prime (21419) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 334 + ... + 392.

It is an arithmetic number, because the mean of its divisors is an integer number (2660).

2²¹⁴¹⁷ is an apocalyptic number.

It is an amenable number.

21417 is a deficient number, since it is larger than the sum of its proper divisors (10503).

21417 is a wasteful number, since it uses less digits than its factorization.

21417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 73 counting only the distinct ones).

The product of its digits is 56, while the sum is 15.

The square root of 21417 is about 146.3454816522. The cubic root of 21417 is about 27.7706606952.

Adding to 21417 its reverse (71412), we get a palindrome (92829).

It can be divided in two parts, 214 and 17, that added together give a triangular number (231 = T₂₁).

The spelling of 21417 in words is "twenty-one thousand, four hundred seventeen", and thus it is an iban number.