661536 has 36 divisors (see below), whose sum is σ = 1882062. Its totient is φ = 220416.

The previous prime is 661517. The next prime is 661541. The reversal of 661536 is 635166.

It can be written as a sum of positive squares in only one way, i.e., 571536 + 90000 = 756^2 + 300^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

661536 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 861 + ... + 1436.

2⁶⁶¹⁵³⁶ is an apocalyptic number.

It is an amenable number.

661536 is an abundant number, since it is smaller than the sum of its proper divisors (1220526).

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

661536 is a wasteful number, since it uses less digits than its factorization.

661536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2313 (or 2302 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 661536 is about 813.3486337359. The cubic root of 661536 is about 87.1333665968.

The spelling of 661536 in words is "six hundred sixty-one thousand, five hundred thirty-six".