19991628 has 36 divisors (see below), whose sum is σ = 50887200. Its totient is φ = 6617376.

The previous prime is 19991627. The next prime is 19991639. The reversal of 19991628 is 82619991.

19991628 is a `hidden beast` number, since 19 + 9 + 9 + 1 + 628 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (19991627) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3501 + ... + 7227.

Almost surely, 2^19991628 is an apocalyptic number.

19991628 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

19991628 is an abundant number, since it is smaller than the sum of its proper divisors (30895572).

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

19991628 is a wasteful number, since it uses less digits than its factorization.

19991628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3886 (or 3881 counting only the distinct ones).

The product of its digits is 69984, while the sum is 45.

The square root of 19991628 is about 4471.1998389694. The cubic root of 19991628 is about 271.4038811996.

The spelling of 19991628 in words is "nineteen million, nine hundred ninety-one thousand, six hundred twenty-eight".