1991530 has 8 divisors (see below), whose sum is σ = 3584772. Its totient is φ = 796608.

The previous prime is 1991527. The next prime is 1991551. The reversal of 1991530 is 351991.

It can be written as a sum of positive squares in 2 ways, for example, as 1979649 + 11881 = 1407^2 + 109^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99567 + ... + 99586.

2^1991530 is an apocalyptic number.

1991530 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991530 is a deficient number, since it is larger than the sum of its proper divisors (1593242).

1991530 is a wasteful number, since it uses less digits than its factorization.

1991530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199160.

The product of its (nonzero) digits is 1215, while the sum is 28.

The square root of 1991530 is about 1411.2157878935. The cubic root of 1991530 is about 125.8139944648.

The spelling of 1991530 in words is "one million, nine hundred ninety-one thousand, five hundred thirty".