1991738 has 16 divisors (see below), whose sum is σ = 3447360. Its totient is φ = 845376.

The previous prime is 1991729. The next prime is 1991753. The reversal of 1991738 is 8371991.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 953 + ... + 2211.

It is an arithmetic number, because the mean of its divisors is an integer number (215460).

2^1991738 is an apocalyptic number.

1991738 is a deficient number, since it is larger than the sum of its proper divisors (1455622).

1991738 is a wasteful number, since it uses less digits than its factorization.

1991738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1381.

The product of its digits is 13608, while the sum is 38.

The square root of 1991738 is about 1411.2894812901. The cubic root of 1991738 is about 125.8183744138.

The spelling of 1991738 in words is "one million, nine hundred ninety-one thousand, seven hundred thirty-eight".