1191209556420 has 576 divisors, whose sum is σ = 4186876861440. Its totient is φ = 282399436800.

The previous prime is 1191209556419. The next prime is 1191209556431. The reversal of 1191209556420 is 246559021911.

1191209556420 is a `hidden beast` number, since 1 + 1 + 91 + 2 + 0 + 9 + 556 + 4 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 204637110 + ... + 204642930.

It is an arithmetic number, because the mean of its divisors is an integer number (7268883440).

Almost surely, 2^{1191209556420} is an apocalyptic number.

1191209556420 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 1191209556420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2093438430720).

1191209556420 is an abundant number, since it is smaller than the sum of its proper divisors (2995667305020).

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

1191209556420 is a wasteful number, since it uses less digits than its factorization.

1191209556420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5978 (or 5964 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The spelling of 1191209556420 in words is "one trillion, one hundred ninety-one billion, two hundred nine million, five hundred fifty-six thousand, four hundred twenty".