66918553 has 16 divisors (see below), whose sum is σ = 75995136. Its totient is φ = 58489920.

The previous prime is 66918547. The next prime is 66918571. The reversal of 66918553 is 35581966.

It is a cyclic number.

It is not a de Polignac number, because 66918553 - 2⁵ = 66918521 is a prime.

It is a super-2 number, since 2×66918553² = 8956185471227618, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66918583) 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, 17175 + ... + 20707.

It is an arithmetic number, because the mean of its divisors is an integer number (4749696).

Almost surely, 2^66918553 is an apocalyptic number.

It is an amenable number.

66918553 is a deficient number, since it is larger than the sum of its proper divisors (9076583).

66918553 is a wasteful number, since it uses less digits than its factorization.

66918553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3624.

The product of its digits is 194400, while the sum is 43.

The square root of 66918553 is about 8180.3760915987. The cubic root of 66918553 is about 405.9901657450.

The spelling of 66918553 in words is "sixty-six million, nine hundred eighteen thousand, five hundred fifty-three".