661802400 has 360 divisors, whose sum is σ = 2760135840. Its totient is φ = 151165440.

The previous prime is 661802389. The next prime is 661802411. The reversal of 661802400 is 4208166.

661802400 is a `hidden beast` number, since 6 + 618 + 0 + 2 + 40 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (661802389) and next prime (661802411).

It is a tau number, because it is divible by the number of its divisors (360).

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 59 ways as a sum of consecutive naturals, for example, 452871 + ... + 454329.

It is an arithmetic number, because the mean of its divisors is an integer number (7667044).

Almost surely, 2^661802400 is an apocalyptic number.

661802400 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 661802400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1380067920).

661802400 is an abundant number, since it is smaller than the sum of its proper divisors (2098333440).

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

661802400 is a wasteful number, since it uses less digits than its factorization.

661802400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1498 (or 1476 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 661802400 is about 25725.5204028995. The cubic root of 661802400 is about 871.4506120531.

The spelling of 661802400 in words is "six hundred sixty-one million, eight hundred two thousand, four hundred".