17978993 has 2 divisors, whose sum is σ = 17978994. Its totient is φ = 17978992.

The previous prime is 17978971. The next prime is 17978999. The reversal of 17978993 is 39987971.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17909824 + 69169 = 4232^2 + 263^2 .

It is a cyclic number.

It is not a de Polignac number, because 17978993 - 2¹⁶ = 17913457 is a prime.

It is not a weakly prime, because it can be changed into another prime (17978999) 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, 8989496 + 8989497.

It is an arithmetic number, because the mean of its divisors is an integer number (8989497).

Almost surely, 2^17978993 is an apocalyptic number.

It is an amenable number.

17978993 is a deficient number, since it is larger than the sum of its proper divisors (1).

17978993 is an equidigital number, since it uses as much as digits as its factorization.

17978993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 857304, while the sum is 53.

The square root of 17978993 is about 4240.1642656859. The cubic root of 17978993 is about 261.9721480406.

The spelling of 17978993 in words is "seventeen million, nine hundred seventy-eight thousand, nine hundred ninety-three".