66655649 has 4 divisors (see below), whose sum is σ = 67245636. Its totient is φ = 66065664.

The previous prime is 66655613. The next prime is 66655661. The reversal of 66655649 is 94655666.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 37149025 + 29506624 = 6095^2 + 5432^2 .

It is a cyclic number.

It is not a de Polignac number, because 66655649 - 2¹² = 66651553 is a prime.

It is a super-2 number, since 2×66655649² = 8885951087222402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66655669) 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, 294824 + ... + 295049.

It is an arithmetic number, because the mean of its divisors is an integer number (16811409).

Almost surely, 2^66655649 is an apocalyptic number.

It is an amenable number.

66655649 is a deficient number, since it is larger than the sum of its proper divisors (589987).

66655649 is a wasteful number, since it uses less digits than its factorization.

66655649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 589986.

The product of its digits is 1166400, while the sum is 47.

The square root of 66655649 is about 8164.2910898620. The cubic root of 66655649 is about 405.4577945829.

The spelling of 66655649 in words is "sixty-six million, six hundred fifty-five thousand, six hundred forty-nine".