661894272 has 192 divisors, whose sum is σ = 2070814200. Its totient is φ = 201719808.

The previous prime is 661894271. The next prime is 661894291. The reversal of 661894272 is 272498166.

It is a happy number.

661894272 is a `hidden beast` number, since 6 + 618 + 9 + 4 + 27 + 2 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 529736256 + 132158016 = 23016^2 + 11496^2 .

It is a tau number, because it is divible by the number of its divisors (192).

It is not an unprimeable number, because it can be changed into a prime (661894271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2890254 + ... + 2890482.

Almost surely, 2^661894272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661894272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1035407100).

661894272 is an abundant number, since it is smaller than the sum of its proper divisors (1408919928).

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

661894272 is a wasteful number, since it uses less digits than its factorization.

661894272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455 (or 440 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 661894272 is about 25727.3059607880. The cubic root of 661894272 is about 871.4909353712.

The spelling of 661894272 in words is "six hundred sixty-one million, eight hundred ninety-four thousand, two hundred seventy-two".