661286400 has 240 divisors, whose sum is σ = 2315302704. Its totient is φ = 165806080.

The previous prime is 661286371. The next prime is 661286413. The reversal of 661286400 is 4682166.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (240).

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 23 ways as a sum of consecutive naturals, for example, 652294 + ... + 653306.

Almost surely, 2^661286400 is an apocalyptic number.

661286400 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 661286400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1157651352).

661286400 is an abundant number, since it is smaller than the sum of its proper divisors (1654016304).

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

661286400 is a wasteful number, since it uses less digits than its factorization.

661286400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1061 (or 1040 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 33.

The square root of 661286400 is about 25715.4894956328. The cubic root of 661286400 is about 871.2240663683.

The spelling of 661286400 in words is "six hundred sixty-one million, two hundred eighty-six thousand, four hundred".