20791217 has 4 divisors (see below), whose sum is σ = 20811840. Its totient is φ = 20770596.

The previous prime is 20791213. The next prime is 20791229. The reversal of 20791217 is 71219702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20791217 - 2² = 20791213 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 20791217.

It is not an unprimeable number, because it can be changed into a prime (20791213) 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, 8717 + ... + 10842.

It is an arithmetic number, because the mean of its divisors is an integer number (5202960).

Almost surely, 2^20791217 is an apocalyptic number.

It is an amenable number.

20791217 is a deficient number, since it is larger than the sum of its proper divisors (20623).

20791217 is a wasteful number, since it uses less digits than its factorization.

20791217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20622.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 20791217 is about 4559.7386986537. The cubic root of 20791217 is about 274.9750588951.

The spelling of 20791217 in words is "twenty million, seven hundred ninety-one thousand, two hundred seventeen".