1821997998 has 48 divisors (see below), whose sum is σ = 4024566000. Its totient is φ = 595553280.

The previous prime is 1821997981. The next prime is 1821998039. The reversal of 1821997998 is 8997991281.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 474928 + ... + 478748.

It is an arithmetic number, because the mean of its divisors is an integer number (83845125).

Almost surely, 2^1821997998 is an apocalyptic number.

1821997998 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1821997998 is an abundant number, since it is smaller than the sum of its proper divisors (2202568002).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1821997998 is a wasteful number, since it uses less digits than its factorization.

1821997998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4337 (or 4334 counting only the distinct ones).

The product of its digits is 5878656, while the sum is 63.

The square root of 1821997998 is about 42684.8684898993. The cubic root of 1821997998 is about 1221.3757654757.

The spelling of 1821997998 in words is "one billion, eight hundred twenty-one million, nine hundred ninety-seven thousand, nine hundred ninety-eight".