661543200 has 432 divisors, whose sum is σ = 2508026976. Its totient is φ = 170035200.

The previous prime is 661543171. The next prime is 661543217. The reversal of 661543200 is 2345166.

661543200 is a `hidden beast` number, since 6 + 615 + 43 + 2 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (432).

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

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, 7970359 + ... + 7970441.

It is an arithmetic number, because the mean of its divisors is an integer number (5805618).

Almost surely, 2^661543200 is an apocalyptic number.

661543200 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 661543200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1254013488).

661543200 is an abundant number, since it is smaller than the sum of its proper divisors (1846483776).

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

661543200 is a wasteful number, since it uses less digits than its factorization.

661543200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 661543200 is about 25720.4821105671. The cubic root of 661543200 is about 871.3368270853.

Adding to 661543200 its reverse (2345166), we get a palindrome (663888366).

The spelling of 661543200 in words is "six hundred sixty-one million, five hundred forty-three thousand, two hundred".