19987993 has 2 divisors, whose sum is σ = 19987994. Its totient is φ = 19987992.

The previous prime is 19987969. The next prime is 19987999. The reversal of 19987993 is 39978991.

19987993 is nontrivially palindromic in base 2.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10673289 + 9314704 = 3267^2 + 3052^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19987993 is a prime.

It is not a weakly prime, because it can be changed into another prime (19987999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9993996 + 9993997.

It is an arithmetic number, because the mean of its divisors is an integer number (9993997).

Almost surely, 2^19987993 is an apocalyptic number.

It is an amenable number.

19987993 is a deficient number, since it is larger than the sum of its proper divisors (1).

19987993 is an equidigital number, since it uses as much as digits as its factorization.

19987993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1102248, while the sum is 55.

The square root of 19987993 is about 4470.7933300478. The cubic root of 19987993 is about 271.3874307650.

The spelling of 19987993 in words is "nineteen million, nine hundred eighty-seven thousand, nine hundred ninety-three".