1999649 has 4 divisors (see below), whose sum is σ = 2002500. Its totient is φ = 1996800.

The previous prime is 1999633. The next prime is 1999651. The reversal of 1999649 is 9469991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1600225 + 399424 = 1265^2 + 632^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999649 - 2⁴ = 1999633 is a prime.

It is a super-2 number, since 2×1999649² = 7997192246402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999619) 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, 449 + ... + 2049.

It is an arithmetic number, because the mean of its divisors is an integer number (500625).

2^1999649 is an apocalyptic number.

It is an amenable number.

1999649 is a deficient number, since it is larger than the sum of its proper divisors (2851).

1999649 is a wasteful number, since it uses less digits than its factorization.

1999649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2850.

The product of its digits is 157464, while the sum is 47.

The square root of 1999649 is about 1414.0894596878. The cubic root of 1999649 is about 125.9847340201.

The spelling of 1999649 in words is "one million, nine hundred ninety-nine thousand, six hundred forty-nine".