2155840 has 28 divisors (see below), whose sum is σ = 5134356. Its totient is φ = 862208.

The previous prime is 2155837. The next prime is 2155841. The reversal of 2155840 is 485512.

2155840 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 937024 + 1218816 = 968^2 + 1104^2 .

It is a super-2 number, since 2×2155840² = 9295292211200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2155841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3049 + ... + 3688.

2^2155840 is an apocalyptic number.

2155840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2155840 is an abundant number, since it is smaller than the sum of its proper divisors (2978516).

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

2155840 is an equidigital number, since it uses as much as digits as its factorization.

2155840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6754 (or 6744 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 2155840 is about 1468.2779028508. The cubic root of 2155840 is about 129.1830424376.

The spelling of 2155840 in words is "two million, one hundred fifty-five thousand, eight hundred forty".