1821998557 has 16 divisors (see below), whose sum is σ = 1899297792. Its totient is φ = 1745948160.

The previous prime is 1821998539. The next prime is 1821998593. The reversal of 1821998557 is 7558991281.

It is a cyclic number.

It is not a de Polignac number, because 1821998557 - 2¹¹ = 1821996509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1821998498 and 1821998507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821998527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1826983 + ... + 1827979.

It is an arithmetic number, because the mean of its divisors is an integer number (118706112).

Almost surely, 2^1821998557 is an apocalyptic number.

It is an amenable number.

1821998557 is a deficient number, since it is larger than the sum of its proper divisors (77299235).

1821998557 is a wasteful number, since it uses less digits than its factorization.

1821998557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1548.

The product of its digits is 1814400, while the sum is 55.

The square root of 1821998557 is about 42684.8750378867. The cubic root of 1821998557 is about 1221.3758903841.

The spelling of 1821998557 in words is "one billion, eight hundred twenty-one million, nine hundred ninety-eight thousand, five hundred fifty-seven".