661484400 has 120 divisors (see below), whose sum is σ = 2155100160. Its totient is φ = 173387520.

The previous prime is 661484381. The next prime is 661484407. The reversal of 661484400 is 4484166.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×661484400² = 875123222886720000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661484407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66129 + ... + 75471.

It is an arithmetic number, because the mean of its divisors is an integer number (17959168).

Almost surely, 2^661484400 is an apocalyptic number.

661484400 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 661484400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1077550080).

661484400 is an abundant number, since it is smaller than the sum of its proper divisors (1493615760).

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

661484400 is a wasteful number, since it uses less digits than its factorization.

661484400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9423 (or 9412 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 33.

The square root of 661484400 is about 25719.3390272767. The cubic root of 661484400 is about 871.3110106188.

The spelling of 661484400 in words is "six hundred sixty-one million, four hundred eighty-four thousand, four hundred".