66605421 has 4 divisors (see below), whose sum is σ = 88807232. Its totient is φ = 44403612.

The previous prime is 66605377. The next prime is 66605449. The reversal of 66605421 is 12450666.

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 not a de Polignac number, because 66605421 - 2⁷ = 66605293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66605221) 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, 11100901 + ... + 11100906.

It is an arithmetic number, because the mean of its divisors is an integer number (22201808).

Almost surely, 2^66605421 is an apocalyptic number.

It is an amenable number.

66605421 is a deficient number, since it is larger than the sum of its proper divisors (22201811).

66605421 is a wasteful number, since it uses less digits than its factorization.

66605421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22201810.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 66605421 is about 8161.2144316885. The cubic root of 66605421 is about 405.3559254892.

The spelling of 66605421 in words is "sixty-six million, six hundred five thousand, four hundred twenty-one".