1921312493 has 2 divisors, whose sum is σ = 1921312494. Its totient is φ = 1921312492.

The previous prime is 1921312397. The next prime is 1921312499. The reversal of 1921312493 is 3942131291.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1872898729 + 48413764 = 43277^2 + 6958^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921312493 - 2²⁶ = 1854203629 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921312499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960656246 + 960656247.

It is an arithmetic number, because the mean of its divisors is an integer number (960656247).

Almost surely, 2^1921312493 is an apocalyptic number.

It is an amenable number.

1921312493 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921312493 is an equidigital number, since it uses as much as digits as its factorization.

1921312493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 35.

The square root of 1921312493 is about 43832.7787506108. The cubic root of 1921312493 is about 1243.1761476586.

The spelling of 1921312493 in words is "one billion, nine hundred twenty-one million, three hundred twelve thousand, four hundred ninety-three".