66555869 has 4 divisors (see below), whose sum is σ = 67214940. Its totient is φ = 65896800.

The previous prime is 66555851. The next prime is 66555887. The reversal of 66555869 is 96855566.

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

It is an interprime number because it is at equal distance from previous prime (66555851) and next prime (66555887).

It can be written as a sum of positive squares in 2 ways, for example, as 59059225 + 7496644 = 7685^2 + 2738^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66555869 is a prime.

It is a super-2 number, since 2×66555869² = 8859367396690322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66555889) 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, 329384 + ... + 329585.

It is an arithmetic number, because the mean of its divisors is an integer number (16803735).

Almost surely, 2^66555869 is an apocalyptic number.

It is an amenable number.

66555869 is a deficient number, since it is larger than the sum of its proper divisors (659071).

66555869 is a wasteful number, since it uses less digits than its factorization.

66555869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659070.

The product of its digits is 1944000, while the sum is 50.

The square root of 66555869 is about 8158.1780441469. The cubic root of 66555869 is about 405.2553772170.

The spelling of 66555869 in words is "sixty-six million, five hundred fifty-five thousand, eight hundred sixty-nine".