1661128560 has 560 divisors, whose sum is σ = 7149584064. Its totient is φ = 349360128.

The previous prime is 1661128559. The next prime is 1661128603. The reversal of 1661128560 is 658211661.

1661128560 is a `hidden beast` number, since 1 + 66 + 11 + 28 + 560 = 666.

It is a tau number, because it is divible by the number of its divisors (560).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 5306964 + ... + 5307276.

Almost surely, 2^1661128560 is an apocalyptic number.

1661128560 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 1661128560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3574792032).

1661128560 is an abundant number, since it is smaller than the sum of its proper divisors (5488455504).

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

1661128560 is a wasteful number, since it uses less digits than its factorization.

1661128560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364 (or 343 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 1661128560 is about 40756.9449296681. The cubic root of 1661128560 is about 1184.3164139422.

The spelling of 1661128560 in words is "one billion, six hundred sixty-one million, one hundred twenty-eight thousand, five hundred sixty".