19910100 has 144 divisors (see below), whose sum is σ = 69440000. Its totient is φ = 4302720.

The previous prime is 19910089. The next prime is 19910113. The reversal of 19910100 is 101991.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39651 + ... + 40149.

Almost surely, 2^19910100 is an apocalyptic number.

19910100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19910100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34720000).

19910100 is an abundant number, since it is smaller than the sum of its proper divisors (49529900).

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

19910100 is a wasteful number, since it uses less digits than its factorization.

19910100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542 (or 535 counting only the distinct ones).

The product of its (nonzero) digits is 81, while the sum is 21.

The square root of 19910100 is about 4462.0735090314. The cubic root of 19910100 is about 271.0344405061.

The spelling of 19910100 in words is "nineteen million, nine hundred ten thousand, one hundred".