661780800 has 168 divisors, whose sum is σ = 2412593600. Its totient is φ = 176463360.

The previous prime is 661780799. The next prime is 661780831. The reversal of 661780800 is 8087166.

661780800 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 23 ways as a sum of consecutive naturals, for example, 35541 + ... + 50859.

Almost surely, 2^661780800 is an apocalyptic number.

661780800 is a gapful number since it is divisible by the number (60) 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 661780800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1206296800).

661780800 is an abundant number, since it is smaller than the sum of its proper divisors (1750812800).

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

661780800 is a wasteful number, since it uses less digits than its factorization.

661780800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15350 (or 15329 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 661780800 is about 25725.1005828937. The cubic root of 661780800 is about 871.4411311073.

The spelling of 661780800 in words is "six hundred sixty-one million, seven hundred eighty thousand, eight hundred".