1155665720 has 64 divisors (see below), whose sum is σ = 2872627200. Its totient is φ = 414910080.

The previous prime is 1155665717. The next prime is 1155665759. The reversal of 1155665720 is 275665511.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18137 + ... + 51383.

It is an arithmetic number, because the mean of its divisors is an integer number (44884800).

Almost surely, 2^1155665720 is an apocalyptic number.

1155665720 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 1155665720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1436313600).

1155665720 is an abundant number, since it is smaller than the sum of its proper divisors (1716961480).

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

1155665720 is a wasteful number, since it uses less digits than its factorization.

1155665720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33348 (or 33344 counting only the distinct ones).

The product of its (nonzero) digits is 63000, while the sum is 38.

The square root of 1155665720 is about 33995.0837622148. The cubic root of 1155665720 is about 1049.4072905818.

The spelling of 1155665720 in words is "one billion, one hundred fifty-five million, six hundred sixty-five thousand, seven hundred twenty".