1921645613 has 2 divisors, whose sum is σ = 1921645614. Its totient is φ = 1921645612.

The previous prime is 1921645603. The next prime is 1921645637. The reversal of 1921645613 is 3165461291.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1568318404 + 353327209 = 39602^2 + 18797^2 .

It is an emirp because it is prime and its reverse (3165461291) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1921645613 - 2¹² = 1921641517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921645603) 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, 960822806 + 960822807.

It is an arithmetic number, because the mean of its divisors is an integer number (960822807).

Almost surely, 2^1921645613 is an apocalyptic number.

It is an amenable number.

1921645613 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921645613 is an equidigital number, since it uses as much as digits as its factorization.

1921645613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 38.

The square root of 1921645613 is about 43836.5784819025. The cubic root of 1921645613 is about 1243.2479914126.

The spelling of 1921645613 in words is "one billion, nine hundred twenty-one million, six hundred forty-five thousand, six hundred thirteen".