66541778 has 4 divisors (see below), whose sum is σ = 99812670. Its totient is φ = 33270888.

The previous prime is 66541753. The next prime is 66541823. The reversal of 66541778 is 87714566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 64754209 + 1787569 = 8047^2 + 1337^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16635443 + ... + 16635446.

Almost surely, 2^66541778 is an apocalyptic number.

66541778 is a deficient number, since it is larger than the sum of its proper divisors (33270892).

66541778 is a wasteful number, since it uses less digits than its factorization.

66541778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33270891.

The product of its digits is 282240, while the sum is 44.

The square root of 66541778 is about 8157.3143864877. The cubic root of 66541778 is about 405.2267753989.

The spelling of 66541778 in words is "sixty-six million, five hundred forty-one thousand, seven hundred seventy-eight".