661936800 has 432 divisors, whose sum is σ = 2606458176. Its totient is φ = 142848000.

The previous prime is 661936789. The next prime is 661936819. The reversal of 661936800 is 8639166.

It is a happy number.

It is a super-3 number, since 3×661936800³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 16144780 + ... + 16144820.

It is an arithmetic number, because the mean of its divisors is an integer number (6033468).

Almost surely, 2^661936800 is an apocalyptic number.

661936800 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 661936800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1303229088).

661936800 is an abundant number, since it is smaller than the sum of its proper divisors (1944521376).

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

661936800 is a wasteful number, since it uses less digits than its factorization.

661936800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 661936800 is about 25728.1324623456. The cubic root of 661936800 is about 871.5095999698.

The spelling of 661936800 in words is "six hundred sixty-one million, nine hundred thirty-six thousand, eight hundred".