19771993 has 4 divisors (see below), whose sum is σ = 19781860. Its totient is φ = 19762128.

The previous prime is 19771987. The next prime is 19772029. The reversal of 19771993 is 39917791.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10843849 + 8928144 = 3293^2 + 2988^2 .

It is a cyclic number.

It is not a de Polignac number, because 19771993 - 2¹⁷ = 19640921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19771943) 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 in 3 ways as a sum of consecutive naturals, for example, 738 + ... + 6331.

It is an arithmetic number, because the mean of its divisors is an integer number (4945465).

Almost surely, 2^19771993 is an apocalyptic number.

It is an amenable number.

19771993 is a deficient number, since it is larger than the sum of its proper divisors (9867).

19771993 is an equidigital number, since it uses as much as digits as its factorization.

19771993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9866.

The product of its digits is 107163, while the sum is 46.

The square root of 19771993 is about 4446.5709260058. The cubic root of 19771993 is about 270.4063064204.

The spelling of 19771993 in words is "nineteen million, seven hundred seventy-one thousand, nine hundred ninety-three".