661023648 has 288 divisors, whose sum is σ = 2117540880. Its totient is φ = 194641920.

The previous prime is 661023647. The next prime is 661023683. The reversal of 661023648 is 846320166.

661023648 is a `hidden beast` number, since 6 + 6 + 1 + 0 + 2 + 3 + 648 = 666.

661023648 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 282643344 + 378380304 = 16812^2 + 19452^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (661023647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7427188 + ... + 7427276.

Almost surely, 2^661023648 is an apocalyptic number.

661023648 is a gapful number since it is divisible by the number (68) 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 661023648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1058770440).

661023648 is an abundant number, since it is smaller than the sum of its proper divisors (1456517232).

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

661023648 is a wasteful number, since it uses less digits than its factorization.

661023648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200 (or 189 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 661023648 is about 25710.3801605499. The cubic root of 661023648 is about 871.1086619125.

The spelling of 661023648 in words is "six hundred sixty-one million, twenty-three thousand, six hundred forty-eight".