17800121 has 2 divisors, whose sum is σ = 17800122. Its totient is φ = 17800120.

The previous prime is 17800117. The next prime is 17800129. The reversal of 17800121 is 12100871.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17732521 + 67600 = 4211^2 + 260^2 .

It is an emirp because it is prime and its reverse (12100871) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 17800121 - 2² = 17800117 is a prime.

It is a super-2 number, since 2×17800121² = 633688615229282, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 17800093 and 17800102.

It is not a weakly prime, because it can be changed into another prime (17800129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8900060 + 8900061.

It is an arithmetic number, because the mean of its divisors is an integer number (8900061).

Almost surely, 2^17800121 is an apocalyptic number.

It is an amenable number.

17800121 is a deficient number, since it is larger than the sum of its proper divisors (1).

17800121 is an equidigital number, since it uses as much as digits as its factorization.

17800121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 17800121 is about 4219.0189617967. The cubic root of 17800121 is about 261.1004687512.

Adding to 17800121 its reverse (12100871), we get a palindrome (29900992).

The spelling of 17800121 in words is "seventeen million, eight hundred thousand, one hundred twenty-one".