661878000 has 640 divisors, whose sum is σ = 2896957440. Its totient is φ = 141004800.

The previous prime is 661877987. The next prime is 661878029. The reversal of 661878000 is 878166.

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 (17) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 6425949 + ... + 6426051.

It is an arithmetic number, because the mean of its divisors is an integer number (4526496).

Almost surely, 2^661878000 is an apocalyptic number.

661878000 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 661878000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1448478720).

661878000 is an abundant number, since it is smaller than the sum of its proper divisors (2235079440).

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

661878000 is a wasteful number, since it uses less digits than its factorization.

661878000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 661878000 is about 25726.9897189702. The cubic root of 661878000 is about 871.4837937388.

The spelling of 661878000 in words is "six hundred sixty-one million, eight hundred seventy-eight thousand".