1191265920 has 256 divisors, whose sum is σ = 4544467200. Its totient is φ = 293179392.

The previous prime is 1191265913. The next prime is 1191265927. The reversal of 1191265920 is 295621911.

It is an interprime number because it is at equal distance from previous prime (1191265913) and next prime (1191265927).

It is a super-2 number, since 2×1191265920² = 2838228984306892800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (1191265927) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 221989 + ... + 227291.

It is an arithmetic number, because the mean of its divisors is an integer number (17751825).

Almost surely, 2^1191265920 is an apocalyptic number.

1191265920 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 1191265920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2272233600).

1191265920 is an abundant number, since it is smaller than the sum of its proper divisors (3353201280).

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

1191265920 is a wasteful number, since it uses less digits than its factorization.

1191265920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5344 (or 5326 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 1191265920 is about 34514.7203378501. The cubic root of 1191265920 is about 1060.0741374514.

The spelling of 1191265920 in words is "one billion, one hundred ninety-one million, two hundred sixty-five thousand, nine hundred twenty".