661132800 has 240 divisors, whose sum is σ = 2427947280. Its totient is φ = 176209920.

The previous prime is 661132781. The next prime is 661132883. The reversal of 661132800 is 8231166.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 344644 + ... + 346556.

It is an arithmetic number, because the mean of its divisors is an integer number (10116447).

Almost surely, 2^661132800 is an apocalyptic number.

661132800 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 661132800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1213973640).

661132800 is an abundant number, since it is smaller than the sum of its proper divisors (1766814480).

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

661132800 is a wasteful number, since it uses less digits than its factorization.

661132800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1950 (or 1923 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 661132800 is about 25712.5027953329. The cubic root of 661132800 is about 871.1566067528.

Adding to 661132800 its reverse (8231166), we get a palindrome (669363966).

The spelling of 661132800 in words is "six hundred sixty-one million, one hundred thirty-two thousand, eight hundred".