1661880 has 64 divisors (see below), whose sum is σ = 5443200. Its totient is φ = 402560.

The previous prime is 1661861. The next prime is 1661887. The reversal of 1661880 is 881661.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661887) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 691 + ... + 1949.

It is an arithmetic number, because the mean of its divisors is an integer number (85050).

2^1661880 is an apocalyptic number.

1661880 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 1661880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2721600).

1661880 is an abundant number, since it is smaller than the sum of its proper divisors (3781320).

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

1661880 is a wasteful number, since it uses less digits than its factorization.

1661880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1284 (or 1280 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 1661880 is about 1289.1392477153. The cubic root of 1661880 is about 118.4494968969.

The spelling of 1661880 in words is "one million, six hundred sixty-one thousand, eight hundred eighty".