20820917 has 4 divisors (see below), whose sum is σ = 22422540. Its totient is φ = 19219296.

The previous prime is 20820889. The next prime is 20820929. The reversal of 20820917 is 71902802.

It is a happy number.

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 10329796 + 10491121 = 3214^2 + 3239^2 .

It is a cyclic number.

It is not a de Polignac number, because 20820917 - 2¹⁰ = 20819893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20820917.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20820967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 800792 + ... + 800817.

It is an arithmetic number, because the mean of its divisors is an integer number (5605635).

Almost surely, 2^20820917 is an apocalyptic number.

It is an amenable number.

20820917 is a deficient number, since it is larger than the sum of its proper divisors (1601623).

20820917 is a wasteful number, since it uses less digits than its factorization.

20820917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1601622.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 20820917 is about 4562.9943019907. The cubic root of 20820917 is about 275.1059294389.

The spelling of 20820917 in words is "twenty million, eight hundred twenty thousand, nine hundred seventeen".