661323600 has 540 divisors, whose sum is σ = 2802829536. Its totient is φ = 143700480.

The previous prime is 661323599. The next prime is 661323643. The reversal of 661323600 is 6323166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 4057119 + ... + 4057281.

Almost surely, 2^661323600 is an apocalyptic number.

661323600 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 661323600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1401414768).

661323600 is an abundant number, since it is smaller than the sum of its proper divisors (2141505936).

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

661323600 is a wasteful number, since it uses less digits than its factorization.

661323600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 27.

The square root of 661323600 is about 25716.2127849339. The cubic root of 661323600 is about 871.2404026726.

Adding to 661323600 its reverse (6323166), we get a palindrome (667646766).

The spelling of 661323600 in words is "six hundred sixty-one million, three hundred twenty-three thousand, six hundred".