1661584320 has 224 divisors, whose sum is σ = 6394947840. Its totient is φ = 402785280.

The previous prime is 1661584313. The next prime is 1661584321. The reversal of 1661584320 is 234851661.

It is a happy number.

1661584320 is a `hidden beast` number, since 1 + 6 + 615 + 8 + 4 + 32 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661584321) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86299 + ... + 103781.

Almost surely, 2^1661584320 is an apocalyptic number.

1661584320 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 1661584320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3197473920).

1661584320 is an abundant number, since it is smaller than the sum of its proper divisors (4733363520).

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

1661584320 is a wasteful number, since it uses less digits than its factorization.

1661584320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17520 (or 17504 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 1661584320 is about 40762.5357405547. The cubic root of 1661584320 is about 1184.4247167560.

The spelling of 1661584320 in words is "one billion, six hundred sixty-one million, five hundred eighty-four thousand, three hundred twenty".