668651426 has 4 divisors (see below), whose sum is σ = 1002977142. Its totient is φ = 334325712.

The previous prime is 668651387. The next prime is 668651443. The reversal of 668651426 is 624156866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 624156866 = 2 ⋅312078433.

It can be written as a sum of positive squares in only one way, i.e., 366760801 + 301890625 = 19151^2 + 17375^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167162855 + ... + 167162858.

Almost surely, 2^668651426 is an apocalyptic number.

668651426 is a deficient number, since it is larger than the sum of its proper divisors (334325716).

668651426 is a wasteful number, since it uses less digits than its factorization.

668651426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334325715.

The product of its digits is 414720, while the sum is 44.

The square root of 668651426 is about 25858.2951100802. The cubic root of 668651426 is about 874.4465293296.

The spelling of 668651426 in words is "six hundred sixty-eight million, six hundred fifty-one thousand, four hundred twenty-six".