21407017 has 4 divisors (see below), whose sum is σ = 22145220. Its totient is φ = 20668816.

The previous prime is 21407011. The next prime is 21407021. The reversal of 21407017 is 71070412.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3463321 + 17943696 = 1861^2 + 4236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21407017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21407011) 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 3 ways as a sum of consecutive naturals, for example, 369058 + ... + 369115.

It is an arithmetic number, because the mean of its divisors is an integer number (5536305).

Almost surely, 2^21407017 is an apocalyptic number.

It is an amenable number.

21407017 is a deficient number, since it is larger than the sum of its proper divisors (738203).

21407017 is an equidigital number, since it uses as much as digits as its factorization.

21407017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738202.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 21407017 is about 4626.7717687390. The cubic root of 21407017 is about 277.6634515779.

Adding to 21407017 its reverse (71070412), we get a palindrome (92477429).

The spelling of 21407017 in words is "twenty-one million, four hundred seven thousand, seventeen".