1661840128 has 144 divisors (see below), whose sum is σ = 3765293280. Its totient is φ = 726663168.

The previous prime is 1661840119. The next prime is 1661840161. The reversal of 1661840128 is 8210481661.

It is a super-2 number, since 2×1661840128² = 5523425222062112768, which contains 22 as substring.

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, 6466176 + ... + 6466432.

It is an arithmetic number, because the mean of its divisors is an integer number (26147870).

Almost surely, 2^1661840128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661840128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1882646640).

1661840128 is an abundant number, since it is smaller than the sum of its proper divisors (2103453152).

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

1661840128 is a wasteful number, since it uses less digits than its factorization.

1661840128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 37.

The square root of 1661840128 is about 40765.6734029992. The cubic root of 1661840128 is about 1184.4854960510.

The spelling of 1661840128 in words is "one billion, six hundred sixty-one million, eight hundred forty thousand, one hundred twenty-eight".