66993409 has 4 divisors (see below), whose sum is σ = 76563904. Its totient is φ = 57422916.

The previous prime is 66993403. The next prime is 66993439. The reversal of 66993409 is 90439966.

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.

It is a cyclic number.

It is not a de Polignac number, because 66993409 - 2¹⁷ = 66862337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66993403) 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, 4785237 + ... + 4785250.

It is an arithmetic number, because the mean of its divisors is an integer number (19140976).

Almost surely, 2^66993409 is an apocalyptic number.

It is an amenable number.

66993409 is a deficient number, since it is larger than the sum of its proper divisors (9570495).

66993409 is an equidigital number, since it uses as much as digits as its factorization.

66993409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9570494.

The product of its (nonzero) digits is 314928, while the sum is 46.

The square root of 66993409 is about 8184.9501525666. The cubic root of 66993409 is about 406.1414913673.

The spelling of 66993409 in words is "sixty-six million, nine hundred ninety-three thousand, four hundred nine".