66561418 has 32 divisors (see below), whose sum is σ = 126355968. Its totient is φ = 25542000.

The previous prime is 66561413. The next prime is 66561437. The reversal of 66561418 is 81416566.

It is not an unprimeable number, because it can be changed into a prime (66561413) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7093 + ... + 13543.

It is an arithmetic number, because the mean of its divisors is an integer number (3948624).

Almost surely, 2^66561418 is an apocalyptic number.

66561418 is a deficient number, since it is larger than the sum of its proper divisors (59794550).

66561418 is a wasteful number, since it uses less digits than its factorization.

66561418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6538.

The product of its digits is 34560, while the sum is 37.

The square root of 66561418 is about 8158.5181252480. The cubic root of 66561418 is about 405.2666394324.

The spelling of 66561418 in words is "sixty-six million, five hundred sixty-one thousand, four hundred eighteen".