17680921 has 2 divisors, whose sum is σ = 17680922. Its totient is φ = 17680920.

The previous prime is 17680903. The next prime is 17680933. The reversal of 17680921 is 12908671.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10471696 + 7209225 = 3236^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 17680921 - 2⁵ = 17680889 is a prime.

It is a super-2 number, since 2×17680921² = 625229934816482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (17680321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8840460 + 8840461.

It is an arithmetic number, because the mean of its divisors is an integer number (8840461).

Almost surely, 2^17680921 is an apocalyptic number.

It is an amenable number.

17680921 is a deficient number, since it is larger than the sum of its proper divisors (1).

17680921 is an equidigital number, since it uses as much as digits as its factorization.

17680921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 17680921 is about 4204.8687256560. The cubic root of 17680921 is about 260.5163358591.

The spelling of 17680921 in words is "seventeen million, six hundred eighty thousand, nine hundred twenty-one".