61666578 has 12 divisors (see below), whose sum is σ = 133610958. Its totient is φ = 20555520.

The previous prime is 61666573. The next prime is 61666589. The reversal of 61666578 is 87566616.

It can be written as a sum of positive squares in only one way, i.e., 56205009 + 5461569 = 7497^2 + 2337^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (61666573) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1712943 + ... + 1712978.

Almost surely, 2^61666578 is an apocalyptic number.

61666578 is an abundant number, since it is smaller than the sum of its proper divisors (71944380).

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

61666578 is a wasteful number, since it uses less digits than its factorization.

61666578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3425929 (or 3425926 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 61666578 is about 7852.8070140555. The cubic root of 61666578 is about 395.0783970868.

The spelling of 61666578 in words is "sixty-one million, six hundred sixty-six thousand, five hundred seventy-eight".