1155990 has 64 divisors (see below), whose sum is σ = 3151872. Its totient is φ = 268800.

The previous prime is 1155977. The next prime is 1155997. The reversal of 1155990 is 995511.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1155997) 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, 10174 + ... + 10286.

It is an arithmetic number, because the mean of its divisors is an integer number (49248).

2^1155990 is an apocalyptic number.

1155990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1155990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1575936).

1155990 is an abundant number, since it is smaller than the sum of its proper divisors (1995882).

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

1155990 is a wasteful number, since it uses less digits than its factorization.

1155990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165.

The product of its (nonzero) digits is 2025, while the sum is 30.

The square root of 1155990 is about 1075.1697540389. The cubic root of 1155990 is about 104.9505436025.

Subtracting from 1155990 its sum of digits (30), we obtain a triangular number (1155960 = T₁₅₂₀).

It can be divided in two parts, 1155 and 990, that added together give a triangular number (2145 = T₆₅).

The spelling of 1155990 in words is "one million, one hundred fifty-five thousand, nine hundred ninety".