66518961 has 4 divisors (see below), whose sum is σ = 88691952. Its totient is φ = 44345972.

The previous prime is 66518957. The next prime is 66518983. The reversal of 66518961 is 16981566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66518961 - 2² = 66518957 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66518941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11086491 + ... + 11086496.

It is an arithmetic number, because the mean of its divisors is an integer number (22172988).

Almost surely, 2^66518961 is an apocalyptic number.

It is an amenable number.

66518961 is a deficient number, since it is larger than the sum of its proper divisors (22172991).

66518961 is a wasteful number, since it uses less digits than its factorization.

66518961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22172990.

The product of its digits is 77760, while the sum is 42.

The square root of 66518961 is about 8155.9157057929. The cubic root of 66518961 is about 405.1804530401.

The spelling of 66518961 in words is "sixty-six million, five hundred eighteen thousand, nine hundred sixty-one".