1821049999 has 4 divisors (see below), whose sum is σ = 1821807720. Its totient is φ = 1820292280.

The previous prime is 1821049987. The next prime is 1821050009. The reversal of 1821049999 is 9999401281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9999401281 = 613 ⋅16312237.

It is a cyclic number.

It is not a de Polignac number, because 1821049999 - 2¹⁷ = 1820918927 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 (1821049969) 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, 375244 + ... + 380065.

It is an arithmetic number, because the mean of its divisors is an integer number (455451930).

Almost surely, 2^1821049999 is an apocalyptic number.

1821049999 is a deficient number, since it is larger than the sum of its proper divisors (757721).

1821049999 is an equidigital number, since it uses as much as digits as its factorization.

1821049999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 757720.

The product of its (nonzero) digits is 419904, while the sum is 52.

The square root of 1821049999 is about 42673.7624190790. The cubic root of 1821049999 is about 1221.1638984523.

The spelling of 1821049999 in words is "one billion, eight hundred twenty-one million, forty-nine thousand, nine hundred ninety-nine".