1961991828 has 96 divisors (see below), whose sum is σ = 5446828800. Its totient is φ = 608560128.

The previous prime is 1961991827. The next prime is 1961991833. The reversal of 1961991828 is 8281991691.

1961991828 is a `hidden beast` number, since 1 + 9 + 619 + 9 + 18 + 2 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961991821) 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 31 ways as a sum of consecutive naturals, for example, 157401 + ... + 169407.

It is an arithmetic number, because the mean of its divisors is an integer number (56737800).

Almost surely, 2^1961991828 is an apocalyptic number.

1961991828 is a gapful number since it is divisible by the number (18) 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 1961991828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2723414400).

1961991828 is an abundant number, since it is smaller than the sum of its proper divisors (3484836972).

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

1961991828 is a wasteful number, since it uses less digits than its factorization.

1961991828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12126 (or 12118 counting only the distinct ones).

The product of its digits is 559872, while the sum is 54.

The square root of 1961991828 is about 44294.3769343243. The cubic root of 1961991828 is about 1251.8887346810. Note that the first 3 decimals are identical.

The spelling of 1961991828 in words is "one billion, nine hundred sixty-one million, nine hundred ninety-one thousand, eight hundred twenty-eight".