21417859 has 4 divisors (see below), whose sum is σ = 21440016. Its totient is φ = 21395704.

The previous prime is 21417839. The next prime is 21417871. The reversal of 21417859 is 95871412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21417859 - 2¹¹ = 21415811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21417829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9559 + ... + 11584.

It is an arithmetic number, because the mean of its divisors is an integer number (5360004).

Almost surely, 2^21417859 is an apocalyptic number.

21417859 is a deficient number, since it is larger than the sum of its proper divisors (22157).

21417859 is a wasteful number, since it uses less digits than its factorization.

21417859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22156.

The product of its digits is 20160, while the sum is 37.

The square root of 21417859 is about 4627.9432796870. The cubic root of 21417859 is about 277.7103196844.

It can be divided in two parts, 2141 and 7859, that added together give a 4-th power (10000 = 10⁴).

The spelling of 21417859 in words is "twenty-one million, four hundred seventeen thousand, eight hundred fifty-nine".