20782217 has 2 divisors, whose sum is σ = 20782218. Its totient is φ = 20782216.

The previous prime is 20782213. The next prime is 20782231. The reversal of 20782217 is 71228702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10471696 + 10310521 = 3236^2 + 3211^2 .

It is a cyclic number.

It is not a de Polignac number, because 20782217 - 2² = 20782213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20782217.

It is not a weakly prime, because it can be changed into another prime (20782213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10391108 + 10391109.

It is an arithmetic number, because the mean of its divisors is an integer number (10391109).

Almost surely, 2^20782217 is an apocalyptic number.

It is an amenable number.

20782217 is a deficient number, since it is larger than the sum of its proper divisors (1).

20782217 is an equidigital number, since it uses as much as digits as its factorization.

20782217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 20782217 is about 4558.7516931722. The cubic root of 20782217 is about 274.9353765506.

The spelling of 20782217 in words is "twenty million, seven hundred eighty-two thousand, two hundred seventeen".