66561736 has 16 divisors (see below), whose sum is σ = 126850140. Its totient is φ = 32735040.

The previous prime is 66561713. The next prime is 66561751. The reversal of 66561736 is 63716566.

It can be written as a sum of positive squares in 2 ways, for example, as 49702500 + 16859236 = 7050^2 + 4106^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67711 + ... + 68686.

Almost surely, 2^66561736 is an apocalyptic number.

It is an amenable number.

66561736 is a deficient number, since it is larger than the sum of its proper divisors (60288404).

66561736 is a wasteful number, since it uses less digits than its factorization.

66561736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136464 (or 136460 counting only the distinct ones).

The product of its digits is 136080, while the sum is 40.

The square root of 66561736 is about 8158.5376140580. The cubic root of 66561736 is about 405.2672848242.

The spelling of 66561736 in words is "sixty-six million, five hundred sixty-one thousand, seven hundred thirty-six".