1155857820 has 96 divisors (see below), whose sum is σ = 3521517888. Its totient is φ = 281567232.

The previous prime is 1155857797. The next prime is 1155857851. The reversal of 1155857820 is 287585511.

It is a congruent number.

It is an unprimeable number.

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, 68022 + ... + 83298.

It is an arithmetic number, because the mean of its divisors is an integer number (36682478).

Almost surely, 2^1155857820 is an apocalyptic number.

1155857820 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 1155857820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1760758944).

1155857820 is an abundant number, since it is smaller than the sum of its proper divisors (2365660068).

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

1155857820 is a wasteful number, since it uses less digits than its factorization.

1155857820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15399 (or 15397 counting only the distinct ones).

The product of its (nonzero) digits is 112000, while the sum is 42.

The square root of 1155857820 is about 33997.9090533521. The cubic root of 1155857820 is about 1049.4654331075.

It can be divided in two parts, 11558 and 57820, that added together give a triangular number (69378 = T₃₇₂).

The spelling of 1155857820 in words is "one billion, one hundred fifty-five million, eight hundred fifty-seven thousand, eight hundred twenty".