2155890 has 64 divisors (see below), whose sum is σ = 5806080. Its totient is φ = 507840.

The previous prime is 2155883. The next prime is 2155931. The reversal of 2155890 is 985512.

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15441 + ... + 15579.

It is an arithmetic number, because the mean of its divisors is an integer number (90720).

2^2155890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2155890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2903040).

2155890 is an abundant number, since it is smaller than the sum of its proper divisors (3650190).

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

2155890 is a wasteful number, since it uses less digits than its factorization.

2155890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207.

The product of its (nonzero) digits is 3600, while the sum is 30.

The square root of 2155890 is about 1468.2949295016. The cubic root of 2155890 is about 129.1840411361.

It can be divided in two parts, 215 and 5890, that added together give a triangular number (6105 = T₁₁₀).

The spelling of 2155890 in words is "two million, one hundred fifty-five thousand, eight hundred ninety".