66444691 has 4 divisors (see below), whose sum is σ = 69941800. Its totient is φ = 62947584.

The previous prime is 66444671. The next prime is 66444731. The reversal of 66444691 is 19644466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19644466 = 2 ⋅9822233.

It is a cyclic number.

It is not a de Polignac number, because 66444691 - 2¹³ = 66436499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66444611) 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, 1748526 + ... + 1748563.

It is an arithmetic number, because the mean of its divisors is an integer number (17485450).

Almost surely, 2^66444691 is an apocalyptic number.

66444691 is a deficient number, since it is larger than the sum of its proper divisors (3497109).

66444691 is a wasteful number, since it uses less digits than its factorization.

66444691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3497108.

The product of its digits is 124416, while the sum is 40.

The square root of 66444691 is about 8151.3612973540. The cubic root of 66444691 is about 405.0295990154.

The spelling of 66444691 in words is "sixty-six million, four hundred forty-four thousand, six hundred ninety-one".