1921813 has 2 divisors, whose sum is σ = 1921814. Its totient is φ = 1921812.

The previous prime is 1921789. The next prime is 1921819. The reversal of 1921813 is 3181291.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1830609 + 91204 = 1353^2 + 302^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921813 - 2⁵ = 1921781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921819) 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, 960906 + 960907.

It is an arithmetic number, because the mean of its divisors is an integer number (960907).

2^1921813 is an apocalyptic number.

It is an amenable number.

1921813 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921813 is an equidigital number, since it uses as much as digits as its factorization.

1921813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 25.

The square root of 1921813 is about 1386.2947017139. The cubic root of 1921813 is about 124.3284088514.

The spelling of 1921813 in words is "one million, nine hundred twenty-one thousand, eight hundred thirteen".