1821997999 has 8 divisors (see below), whose sum is σ = 1881525888. Its totient is φ = 1762517280.

The previous prime is 1821997981. The next prime is 1821998039. The reversal of 1821997999 is 9997991281.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1821997999 - 2¹⁵ = 1821965231 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1821997999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821997909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77589 + ... + 98305.

It is an arithmetic number, because the mean of its divisors is an integer number (235190736).

Almost surely, 2^1821997999 is an apocalyptic number.

1821997999 is a deficient number, since it is larger than the sum of its proper divisors (59527889).

1821997999 is a wasteful number, since it uses less digits than its factorization.

1821997999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23585.

The product of its digits is 6613488, while the sum is 64.

The square root of 1821997999 is about 42684.8685016131. The cubic root of 1821997999 is about 1221.3757656991.

The spelling of 1821997999 in words is "one billion, eight hundred twenty-one million, nine hundred ninety-seven thousand, nine hundred ninety-nine".