191819920 has 80 divisors (see below), whose sum is σ = 467046000. Its totient is φ = 73170944.

The previous prime is 191819893. The next prime is 191819923. The reversal of 191819920 is 29918191.

191819920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 52012944 + 139806976 = 7212^2 + 11824^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (191819923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 206016 + ... + 206944.

It is an arithmetic number, because the mean of its divisors is an integer number (5838075).

Almost surely, 2^191819920 is an apocalyptic number.

191819920 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 191819920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (233523000).

191819920 is an abundant number, since it is smaller than the sum of its proper divisors (275226080).

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

191819920 is a wasteful number, since it uses less digits than its factorization.

191819920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060 (or 1054 counting only the distinct ones).

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

The square root of 191819920 is about 13849.9068588926. The cubic root of 191819920 is about 576.7194103843.

The spelling of 191819920 in words is "one hundred ninety-one million, eight hundred nineteen thousand, nine hundred twenty".