1661550720 has 128 divisors (see below), whose sum is σ = 5320728000. Its totient is φ = 441028608.

The previous prime is 1661550719. The next prime is 1661550731. The reversal of 1661550720 is 270551661.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 437791 + ... + 441569.

Almost surely, 2^1661550720 is an apocalyptic number.

1661550720 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 1661550720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2660364000).

1661550720 is an abundant number, since it is smaller than the sum of its proper divisors (3659177280).

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

1661550720 is a wasteful number, since it uses less digits than its factorization.

1661550720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4030 (or 4018 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 33.

The square root of 1661550720 is about 40762.1235953182. The cubic root of 1661550720 is about 1184.4167330226.

The spelling of 1661550720 in words is "one billion, six hundred sixty-one million, five hundred fifty thousand, seven hundred twenty".