18420517 has 2 divisors, whose sum is σ = 18420518. Its totient is φ = 18420516.

The previous prime is 18420491. The next prime is 18420533. The reversal of 18420517 is 71502481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15319396 + 3101121 = 3914^2 + 1761^2 .

It is a cyclic number.

It is not a de Polignac number, because 18420517 - 2¹⁵ = 18387749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18420587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9210258 + 9210259.

It is an arithmetic number, because the mean of its divisors is an integer number (9210259).

Almost surely, 2^18420517 is an apocalyptic number.

It is an amenable number.

18420517 is a deficient number, since it is larger than the sum of its proper divisors (1).

18420517 is an equidigital number, since it uses as much as digits as its factorization.

18420517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 18420517 is about 4291.9129767506. The cubic root of 18420517 is about 264.0993131478.

Adding to 18420517 its reverse (71502481), we get a palindrome (89922998).

The spelling of 18420517 in words is "eighteen million, four hundred twenty thousand, five hundred seventeen".