431665621 has 4 divisors (see below), whose sum is σ = 434160972. Its totient is φ = 429170272.

The previous prime is 431665613. The next prime is 431665631. The reversal of 431665621 is 126566134.

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 417752721 + 13912900 = 20439^2 + 3730^2 .

It is a cyclic number.

It is not a de Polignac number, because 431665621 - 2³ = 431665613 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 (431665601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1247416 + ... + 1247761.

It is an arithmetic number, because the mean of its divisors is an integer number (108540243).

Almost surely, 2^431665621 is an apocalyptic number.

It is an amenable number.

431665621 is a deficient number, since it is larger than the sum of its proper divisors (2495351).

431665621 is a wasteful number, since it uses less digits than its factorization.

431665621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2495350.

The product of its digits is 25920, while the sum is 34.

The square root of 431665621 is about 20776.5642251071. The cubic root of 431665621 is about 755.7575373979.

The spelling of 431665621 in words is "four hundred thirty-one million, six hundred sixty-five thousand, six hundred twenty-one".