1991928 has 16 divisors (see below), whose sum is σ = 4979880. Its totient is φ = 663968.

The previous prime is 1991921. The next prime is 1991929. The reversal of 1991928 is 8291991.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991921) 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, 41475 + ... + 41522.

2^1991928 is an apocalyptic number.

It is an amenable number.

1991928 is an abundant number, since it is smaller than the sum of its proper divisors (2987952).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1991928 is a wasteful number, since it uses less digits than its factorization.

1991928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83006 (or 83002 counting only the distinct ones).

The product of its digits is 11664, while the sum is 39.

The square root of 1991928 is about 1411.3567940106. The cubic root of 1991928 is about 125.8223750624.

The spelling of 1991928 in words is "one million, nine hundred ninety-one thousand, nine hundred twenty-eight".