1605990 has 64 divisors (see below), whose sum is σ = 4230144. Its totient is φ = 388608.

The previous prime is 1605979. The next prime is 1606009. The reversal of 1605990 is 995061.

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

It is a congruent 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, 23937 + ... + 24003.

It is an arithmetic number, because the mean of its divisors is an integer number (66096).

2^1605990 is an apocalyptic number.

1605990 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 1605990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2115072).

1605990 is an abundant number, since it is smaller than the sum of its proper divisors (2624154).

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

1605990 is a wasteful number, since it uses less digits than its factorization.

1605990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141.

The product of its (nonzero) digits is 2430, while the sum is 30.

The square root of 1605990 is about 1267.2766075329. The cubic root of 1605990 is about 117.1064849827.

The spelling of 1605990 in words is "one million, six hundred five thousand, nine hundred ninety".