668216069 has 4 divisors (see below), whose sum is σ = 670199244. Its totient is φ = 666232896.

The previous prime is 668216063. The next prime is 668216077. The reversal of 668216069 is 960612866.

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 420783169 + 247432900 = 20513^2 + 15730^2 .

It is a cyclic number.

It is not a de Polignac number, because 668216069 - 2⁸ = 668215813 is a prime.

It is a super-2 number, since 2×668216069² = 893025429739625522, 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 (668216063) 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, 991082 + ... + 991755.

It is an arithmetic number, because the mean of its divisors is an integer number (167549811).

Almost surely, 2^668216069 is an apocalyptic number.

It is an amenable number.

668216069 is a deficient number, since it is larger than the sum of its proper divisors (1983175).

668216069 is a wasteful number, since it uses less digits than its factorization.

668216069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1983174.

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 668216069 is about 25849.8756089850. The cubic root of 668216069 is about 874.2567049277.

The spelling of 668216069 in words is "six hundred sixty-eight million, two hundred sixteen thousand, sixty-nine".