661478400000 has 1680 divisors, whose sum is σ = 2787491432880. Its totient is φ = 154828800000.

The previous prime is 661478399983. The next prime is 661478400031. The reversal of 661478400000 is 4874166.

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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 22809599986 + ... + 22809600014.

It is an arithmetic number, because the mean of its divisors is an integer number (1659221091).

Almost surely, 2^661478400000 is an apocalyptic number.

661478400000 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 661478400000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1393745716440).

661478400000 is an abundant number, since it is smaller than the sum of its proper divisors (2126013032880).

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

661478400000 is an frugal number, since it uses more digits than its factorization.

661478400000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The spelling of 661478400000 in words is "six hundred sixty-one billion, four hundred seventy-eight million, four hundred thousand".