1991560 has 16 divisors (see below), whose sum is σ = 4481100. Its totient is φ = 796608.

The previous prime is 1991551. The next prime is 1991573. The reversal of 1991560 is 651991.

It can be written as a sum of positive squares in 2 ways, for example, as 1887876 + 103684 = 1374^2 + 322^2 .

It is a super-2 number, since 2×1991560² = 7932622467200, which contains 22 as substring.

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, 24855 + ... + 24934.

2^1991560 is an apocalyptic number.

1991560 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991560 is an abundant number, since it is smaller than the sum of its proper divisors (2489540).

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

1991560 is a wasteful number, since it uses less digits than its factorization.

1991560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49800 (or 49796 counting only the distinct ones).

The product of its (nonzero) digits is 2430, while the sum is 31.

The square root of 1991560 is about 1411.2264169863. The cubic root of 1991560 is about 125.8146262070.

The spelling of 1991560 in words is "one million, nine hundred ninety-one thousand, five hundred sixty".