1821493789 has 4 divisors (see below), whose sum is σ = 1860249024. Its totient is φ = 1782738556.

The previous prime is 1821493783. The next prime is 1821493829. The reversal of 1821493789 is 9873941281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9873941281 = 3719 ⋅2654999.

It is a cyclic number.

It is not a de Polignac number, because 1821493789 - 2²¹ = 1819396637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821493783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19377547 + ... + 19377640.

It is an arithmetic number, because the mean of its divisors is an integer number (465062256).

Almost surely, 2^1821493789 is an apocalyptic number.

It is an amenable number.

1821493789 is a deficient number, since it is larger than the sum of its proper divisors (38755235).

1821493789 is an equidigital number, since it uses as much as digits as its factorization.

1821493789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38755234.

The product of its digits is 870912, while the sum is 52.

The square root of 1821493789 is about 42678.9619016208. The cubic root of 1821493789 is about 1221.2630896349.

The spelling of 1821493789 in words is "one billion, eight hundred twenty-one million, four hundred ninety-three thousand, seven hundred eighty-nine".