661556250 has 144 divisors (see below), whose sum is σ = 1888941600. Its totient is φ = 166860000.

The previous prime is 661556243. The next prime is 661556251. The reversal of 661556250 is 52655166.

It is a happy number.

661556250 is digitally balanced in base 2 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (661556251) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1068441 + ... + 1069059.

It is an arithmetic number, because the mean of its divisors is an integer number (13117650).

Almost surely, 2^661556250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661556250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (944470800).

661556250 is an abundant number, since it is smaller than the sum of its proper divisors (1227385350).

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

661556250 is a wasteful number, since it uses less digits than its factorization.

661556250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 661556250 is about 25720.7357981843. The cubic root of 661556250 is about 871.3425565528.

The spelling of 661556250 in words is "six hundred sixty-one million, five hundred fifty-six thousand, two hundred fifty".