1990638 has 48 divisors (see below), whose sum is σ = 4769856. Its totient is φ = 596160.

The previous prime is 1990621. The next prime is 1990643. The reversal of 1990638 is 8360991.

1990638 is a `hidden beast` number, since 19 + 9 + 0 + 638 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10908 + ... + 11088.

It is an arithmetic number, because the mean of its divisors is an integer number (99372).

2^1990638 is an apocalyptic number.

1990638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1990638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2384928).

1990638 is an abundant number, since it is smaller than the sum of its proper divisors (2779218).

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

1990638 is a wasteful number, since it uses less digits than its factorization.

1990638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 246 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 1990638 is about 1410.8997129492. The cubic root of 1990638 is about 125.7952077627.

It can be divided in two parts, 1990 and 638, that added together give a triangular number (2628 = T₇₂).

The spelling of 1990638 in words is "one million, nine hundred ninety thousand, six hundred thirty-eight".