66732561 has 27 divisors (see below), whose sum is σ = 112417851. Its totient is φ = 38034864.

The previous prime is 66732559. The next prime is 66732569. The reversal of 66732561 is 16523766.

The square root of 66732561 is 8169.

It is a perfect power (a square), and thus also a powerful number.

66732561 is a `hidden beast` number, since 6 + 67 + 32 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 15752961 + 50979600 = 3969^2 + 7140^2 .

It is not a de Polignac number, because 66732561 - 2¹ = 66732559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66732569) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 171355 + ... + 171743.

Almost surely, 2^66732561 is an apocalyptic number.

66732561 is the 8169-th square number.

66732561 is the 4085-th centered octagonal number.

It is an amenable number.

66732561 is a deficient number, since it is larger than the sum of its proper divisors (45685290).

66732561 is an equidigital number, since it uses as much as digits as its factorization.

66732561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798 (or 399 counting only the distinct ones).

The product of its digits is 45360, while the sum is 36.

The cubic root of 66732561 is about 405.6136832621.

Multiplying 66732561 by its sum of digits (36), we get a square (2402372196 = 49014²).

The spelling of 66732561 in words is "sixty-six million, seven hundred thirty-two thousand, five hundred sixty-one".