19991028 has 12 divisors (see below), whose sum is σ = 46645760. Its totient is φ = 6663672.

The previous prime is 19991011. The next prime is 19991039. The reversal of 19991028 is 82019991.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 832948 + ... + 832971.

Almost surely, 2^19991028 is an apocalyptic number.

It is an amenable number.

19991028 is an abundant number, since it is smaller than the sum of its proper divisors (26654732).

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

19991028 is a wasteful number, since it uses less digits than its factorization.

19991028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1665926 (or 1665924 counting only the distinct ones).

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

The square root of 19991028 is about 4471.1327423820. The cubic root of 19991028 is about 271.4011659971.

The spelling of 19991028 in words is "nineteen million, nine hundred ninety-one thousand, twenty-eight".