1991290 has 16 divisors (see below), whose sum is σ = 4096512. Its totient is φ = 682704.

The previous prime is 1991281. The next prime is 1991293. The reversal of 1991290 is 921991.

It is not an unprimeable number, because it can be changed into a prime (1991293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14154 + ... + 14293.

It is an arithmetic number, because the mean of its divisors is an integer number (256032).

2^1991290 is an apocalyptic number.

1991290 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991290 is an abundant number, since it is smaller than the sum of its proper divisors (2105222).

1991290 is a wasteful number, since it uses less digits than its factorization.

1991290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28461.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 1991290 is about 1411.1307522693. The cubic root of 1991290 is about 125.8089402984.

It can be divided in two parts, 19912 and 90, that added together give a palindrome (20002).

The spelling of 1991290 in words is "one million, nine hundred ninety-one thousand, two hundred ninety".