1909191820 has 72 divisors (see below), whose sum is σ = 4415783904. Its totient is φ = 691967232.

The previous prime is 1909191803. The next prime is 1909191821. The reversal of 1909191820 is 281919091.

It is a super-3 number, since 3×1909191820³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1909191821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 160312 + ... + 171808.

It is an arithmetic number, because the mean of its divisors is an integer number (61330332).

Almost surely, 2^1909191820 is an apocalyptic number.

1909191820 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 1909191820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2207891952).

1909191820 is an abundant number, since it is smaller than the sum of its proper divisors (2506592084).

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

1909191820 is a wasteful number, since it uses less digits than its factorization.

1909191820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11567 (or 11546 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 40.

The square root of 1909191820 is about 43694.2996282124. The cubic root of 1909191820 is about 1240.5564230167.

The spelling of 1909191820 in words is "one billion, nine hundred nine million, one hundred ninety-one thousand, eight hundred twenty".