661750221 has 16 divisors (see below), whose sum is σ = 1013207040. Its totient is φ = 379951920.

The previous prime is 661750213. The next prime is 661750237. The reversal of 661750221 is 122057166.

661750221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661750221 - 2³ = 661750213 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661750121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 527085 + ... + 528338.

It is an arithmetic number, because the mean of its divisors is an integer number (63325440).

Almost surely, 2^661750221 is an apocalyptic number.

It is an amenable number.

661750221 is a deficient number, since it is larger than the sum of its proper divisors (351456819).

661750221 is a wasteful number, since it uses less digits than its factorization.

661750221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1055456.

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 661750221 is about 25724.5062343284. The cubic root of 661750221 is about 871.4277086323.

The spelling of 661750221 in words is "six hundred sixty-one million, seven hundred fifty thousand, two hundred twenty-one".