21317807 has 8 divisors (see below), whose sum is σ = 24600576. Its totient is φ = 18094392.

The previous prime is 21317759. The next prime is 21317833. The reversal of 21317807 is 70871312.

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 21317807 - 2¹⁰ = 21316783 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21317807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317887) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14063 + ... + 15504.

It is an arithmetic number, because the mean of its divisors is an integer number (3075072).

Almost surely, 2^21317807 is an apocalyptic number.

21317807 is a deficient number, since it is larger than the sum of its proper divisors (3282769).

21317807 is a wasteful number, since it uses less digits than its factorization.

21317807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29677.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 21317807 is about 4617.1210727032. The cubic root of 21317807 is about 277.2772099216.

The spelling of 21317807 in words is "twenty-one million, three hundred seventeen thousand, eight hundred seven".