661239936 has 192 divisors, whose sum is σ = 2255897280. Its totient is φ = 188863488.

The previous prime is 661239911. The next prime is 661239947. The reversal of 661239936 is 639932166.

It is a happy number.

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

It is a super-2 number, since 2×661239936² = 874476505922568192, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 661239891 and 661239900.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 216210 + ... + 219246.

It is an arithmetic number, because the mean of its divisors is an integer number (11749465).

Almost surely, 2^661239936 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 661239936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1127948640).

661239936 is an abundant number, since it is smaller than the sum of its proper divisors (1594657344).

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

661239936 is an equidigital number, since it uses as much as digits as its factorization.

661239936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3073 (or 3049 counting only the distinct ones).

The product of its digits is 314928, while the sum is 45.

The square root of 661239936 is about 25714.5860553889. The cubic root of 661239936 is about 871.2036609367.

The spelling of 661239936 in words is "six hundred sixty-one million, two hundred thirty-nine thousand, nine hundred thirty-six".