1999990 has 8 divisors (see below), whose sum is σ = 3600000. Its totient is φ = 799992.

The previous prime is 1999979. The next prime is 1999993. The reversal of 1999990 is 999991.

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

It is a self number, because there is not a number n which added to its sum of digits gives 1999990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99990 + ... + 100009.

It is an arithmetic number, because the mean of its divisors is an integer number (450000).

2^1999990 is an apocalyptic number.

1999990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1999990 is a deficient number, since it is larger than the sum of its proper divisors (1600010).

1999990 is a wasteful number, since it uses less digits than its factorization.

1999990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200006.

The product of its (nonzero) digits is 59049, while the sum is 46.

The square root of 1999990 is about 1414.2100268348. The cubic root of 1999990 is about 125.9918950023.

Subtracting from 1999990 its reverse (999991), we obtain a palindrome (999999).

The spelling of 1999990 in words is "one million, nine hundred ninety-nine thousand, nine hundred ninety".