1991630238 has 64 divisors (see below), whose sum is σ = 4368555072. Its totient is φ = 601620480.

The previous prime is 1991630213. The next prime is 1991630243. The reversal of 1991630238 is 8320361991.

It is a self number, because there is not a number n which added to its sum of digits gives 1991630238.

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, 1462678 + ... + 1464038.

It is an arithmetic number, because the mean of its divisors is an integer number (68258673).

Almost surely, 2^1991630238 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991630238, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2184277536).

1991630238 is an abundant number, since it is smaller than the sum of its proper divisors (2376924834).

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

1991630238 is a wasteful number, since it uses less digits than its factorization.

1991630238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1709.

The product of its (nonzero) digits is 69984, while the sum is 42.

The square root of 1991630238 is about 44627.6846587407. The cubic root of 1991630238 is about 1258.1610525927.

The spelling of 1991630238 in words is "one billion, nine hundred ninety-one million, six hundred thirty thousand, two hundred thirty-eight".