1661100 has 108 divisors (see below), whose sum is σ = 5640264. Its totient is φ = 376320.

The previous prime is 1661069. The next prime is 1661111. The reversal of 1661100 is 11661.

It is a Harshad number since it is a multiple of its sum of digits (15).

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 1661100.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 14644 + ... + 14756.

2^1661100 is an apocalyptic number.

1661100 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 1661100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2820132).

1661100 is an abundant number, since it is smaller than the sum of its proper divisors (3979164).

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

1661100 is a wasteful number, since it uses less digits than its factorization.

1661100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 1661100 is about 1288.8366847665. The cubic root of 1661100 is about 118.4309626534.

Adding to 1661100 its reverse (11661), we get a palindrome (1672761).

It can be divided in two parts, 16 and 61100, that added together give a palindrome (61116).

The spelling of 1661100 in words is "one million, six hundred sixty-one thousand, one hundred".