668752621 has 4 divisors (see below), whose sum is σ = 678171744. Its totient is φ = 659333500.

The previous prime is 668752619. The next prime is 668752649. The reversal of 668752621 is 126257866.

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 a cyclic number.

It is not a de Polignac number, because 668752621 - 2¹ = 668752619 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 (668752691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4709455 + ... + 4709596.

It is an arithmetic number, because the mean of its divisors is an integer number (169542936).

Almost surely, 2^668752621 is an apocalyptic number.

It is an amenable number.

668752621 is a deficient number, since it is larger than the sum of its proper divisors (9419123).

668752621 is an equidigital number, since it uses as much as digits as its factorization.

668752621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9419122.

The product of its digits is 241920, while the sum is 43.

The square root of 668752621 is about 25860.2517582486. The cubic root of 668752621 is about 874.4906405807.

It can be divided in two parts, 66875 and 2621, that added together give a palindrome (69496).

The spelling of 668752621 in words is "six hundred sixty-eight million, seven hundred fifty-two thousand, six hundred twenty-one".