1991600 has 60 divisors (see below), whose sum is σ = 5166336. Its totient is φ = 733440.

The previous prime is 1991597. The next prime is 1991603. The reversal of 1991600 is 61991.

It is an interprime number because it is at equal distance from previous prime (1991597) and next prime (1991603).

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 1991600.

It is not an unprimeable number, because it can be changed into a prime (1991603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5009 + ... + 5391.

2^1991600 is an apocalyptic number.

1991600 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2583168).

1991600 is an abundant number, since it is smaller than the sum of its proper divisors (3174736).

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

1991600 is a wasteful number, since it uses less digits than its factorization.

1991600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414 (or 403 counting only the distinct ones).

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 1991600 is about 1411.2405889855. The cubic root of 1991600 is about 125.8154685202.

It can be divided in two parts, 19 and 91600, that added together give a palindrome (91619).

The spelling of 1991600 in words is "one million, nine hundred ninety-one thousand, six hundred".