665832421 has 8 divisors (see below), whose sum is σ = 705297240. Its totient is φ = 626400768.

The previous prime is 665832389. The next prime is 665832439. The reversal of 665832421 is 124238566.

It can be written as a sum of positive squares in 4 ways, for example, as 364428100 + 301404321 = 19090^2 + 17361^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 665832421 - 2⁵ = 665832389 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 (665832491) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41715 + ... + 55423.

It is an arithmetic number, because the mean of its divisors is an integer number (88162155).

Almost surely, 2^665832421 is an apocalyptic number.

It is an amenable number.

665832421 is a deficient number, since it is larger than the sum of its proper divisors (39464819).

665832421 is a wasteful number, since it uses less digits than its factorization.

665832421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16583.

The product of its digits is 69120, while the sum is 37.

The square root of 665832421 is about 25803.7288196881. The cubic root of 665832421 is about 873.2159222764.

The spelling of 665832421 in words is "six hundred sixty-five million, eight hundred thirty-two thousand, four hundred twenty-one".