1661040000 has 320 divisors, whose sum is σ = 6133974000. Its totient is φ = 442368000.

The previous prime is 1661039999. The next prime is 1661040053. The reversal of 1661040000 is 401661.

1661040000 is a `hidden beast` number, since 1 + 661 + 0 + 4 + 0 + 0 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2159616 + ... + 2160384.

Almost surely, 2^1661040000 is an apocalyptic number.

1661040000 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 1661040000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3066987000).

1661040000 is an abundant number, since it is smaller than the sum of its proper divisors (4472934000).

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

1661040000 is an frugal number, since it uses more digits than its factorization.

1661040000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812 (or 779 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1661040000 is about 40755.8584745801. The cubic root of 1661040000 is about 1184.2953670210.

Adding to 1661040000 its reverse (401661), we get a palindrome (1661441661).

The spelling of 1661040000 in words is "one billion, six hundred sixty-one million, forty thousand".