1990665 has 24 divisors (see below), whose sum is σ = 3564288. Its totient is φ = 1026720.

The previous prime is 1990661. The next prime is 1990679. The reversal of 1990665 is 5660991.

It is not a de Polignac number, because 1990665 - 2² = 1990661 is a prime.

It is a Curzon number.

1990665 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1990661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 682 + ... + 2108.

It is an arithmetic number, because the mean of its divisors is an integer number (148512).

2^1990665 is an apocalyptic number.

1990665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1990665 is a deficient number, since it is larger than the sum of its proper divisors (1573623).

1990665 is a wasteful number, since it uses less digits than its factorization.

1990665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1469 (or 1466 counting only the distinct ones).

The product of its (nonzero) digits is 14580, while the sum is 36.

The square root of 1990665 is about 1410.9092812793. The cubic root of 1990665 is about 125.7957765008.

The spelling of 1990665 in words is "one million, nine hundred ninety thousand, six hundred sixty-five".