661516800 has 480 divisors, whose sum is σ = 2630403072. Its totient is φ = 143278080.

The previous prime is 661516783. The next prime is 661516813. The reversal of 661516800 is 8615166.

It is a tau number, because it is divible by the number of its divisors (480).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6182347 + ... + 6182453.

Almost surely, 2^661516800 is an apocalyptic number.

661516800 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 661516800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1315201536).

661516800 is an abundant number, since it is smaller than the sum of its proper divisors (1968886272).

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

661516800 is a wasteful number, since it uses less digits than its factorization.

661516800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 661516800 is about 25719.9688957821. The cubic root of 661516800 is about 871.3252362080.

The spelling of 661516800 in words is "six hundred sixty-one million, five hundred sixteen thousand, eight hundred".