66637321 has 4 divisors (see below), whose sum is σ = 68786944. Its totient is φ = 64487700.

The previous prime is 66637309. The next prime is 66637349. The reversal of 66637321 is 12373666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12373666 = 2 ⋅6186833.

It is a cyclic number.

It is not a de Polignac number, because 66637321 - 2⁵ = 66637289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66637381) 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, 1074765 + ... + 1074826.

It is an arithmetic number, because the mean of its divisors is an integer number (17196736).

Almost surely, 2^66637321 is an apocalyptic number.

It is an amenable number.

66637321 is a deficient number, since it is larger than the sum of its proper divisors (2149623).

66637321 is a wasteful number, since it uses less digits than its factorization.

66637321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2149622.

The product of its digits is 27216, while the sum is 34.

The square root of 66637321 is about 8163.1685637380. The cubic root of 66637321 is about 405.4206288823.

The spelling of 66637321 in words is "sixty-six million, six hundred thirty-seven thousand, three hundred twenty-one".