66717421 has 4 divisors (see below), whose sum is σ = 66800700. Its totient is φ = 66634144.

The previous prime is 66717397. The next prime is 66717433. The reversal of 66717421 is 12471766.

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 63776196 + 2941225 = 7986^2 + 1715^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66717421 is a prime.

It is a super-3 number, since 3×66717421³ (a number of 24 digits) contains 333 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 (66717481) 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, 40426 + ... + 42043.

It is an arithmetic number, because the mean of its divisors is an integer number (16700175).

Almost surely, 2^66717421 is an apocalyptic number.

It is an amenable number.

66717421 is a deficient number, since it is larger than the sum of its proper divisors (83279).

66717421 is an equidigital number, since it uses as much as digits as its factorization.

66717421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83278.

The product of its digits is 14112, while the sum is 34.

The square root of 66717421 is about 8168.0732734226. The cubic root of 66717421 is about 405.5830063055.

The spelling of 66717421 in words is "sixty-six million, seven hundred seventeen thousand, four hundred twenty-one".