663243421 has 4 divisors (see below), whose sum is σ = 667077372. Its totient is φ = 659409472.

The previous prime is 663243409. The next prime is 663243487. The reversal of 663243421 is 124342366.

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 393824025 + 269419396 = 19845^2 + 16414^2 .

It is a cyclic number.

It is not a de Polignac number, because 663243421 - 2⁷ = 663243293 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 (663243401) 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, 1916716 + ... + 1917061.

It is an arithmetic number, because the mean of its divisors is an integer number (166769343).

Almost surely, 2^663243421 is an apocalyptic number.

It is an amenable number.

663243421 is a deficient number, since it is larger than the sum of its proper divisors (3833951).

663243421 is a wasteful number, since it uses less digits than its factorization.

663243421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3833950.

The product of its digits is 20736, while the sum is 31.

The square root of 663243421 is about 25753.5127895206. The cubic root of 663243421 is about 872.0826578527.

Adding to 663243421 its reverse (124342366), we get a palindrome (787585787).

The spelling of 663243421 in words is "six hundred sixty-three million, two hundred forty-three thousand, four hundred twenty-one".