20971817 has 4 divisors (see below), whose sum is σ = 21002436. Its totient is φ = 20941200.

The previous prime is 20971807. The next prime is 20971889. The reversal of 20971817 is 71817902.

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 18627856 + 2343961 = 4316^2 + 1531^2 .

It is a cyclic number.

It is not a de Polignac number, because 20971817 - 2¹⁴ = 20955433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20971807) 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, 14258 + ... + 15659.

It is an arithmetic number, because the mean of its divisors is an integer number (5250609).

Almost surely, 2^20971817 is an apocalyptic number.

It is an amenable number.

20971817 is a deficient number, since it is larger than the sum of its proper divisors (30619).

20971817 is an equidigital number, since it uses as much as digits as its factorization.

20971817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30618.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20971817 is about 4579.4996451578. The cubic root of 20971817 is about 275.7689421309.

The spelling of 20971817 in words is "twenty million, nine hundred seventy-one thousand, eight hundred seventeen".