664002421 has 8 divisors (see below), whose sum is σ = 685168344. Its totient is φ = 643073280.

The previous prime is 664002403. The next prime is 664002499. The reversal of 664002421 is 124200466.

It can be written as a sum of positive squares in 4 ways, for example, as 83722500 + 580279921 = 9150^2 + 24089^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 664002421 - 2⁷ = 664002293 is a prime.

It is a super-2 number, since 2×664002421² = 881798430187722482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664002401) 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, 53490 + ... + 64723.

It is an arithmetic number, because the mean of its divisors is an integer number (85646043).

Almost surely, 2^664002421 is an apocalyptic number.

It is an amenable number.

664002421 is a deficient number, since it is larger than the sum of its proper divisors (21165923).

664002421 is a wasteful number, since it uses less digits than its factorization.

664002421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118391.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 664002421 is about 25768.2444299180. The cubic root of 664002421 is about 872.4151945882.

Adding to 664002421 its reverse (124200466), we get a palindrome (788202887).

The spelling of 664002421 in words is "six hundred sixty-four million, two thousand, four hundred twenty-one".