656667647 has 2 divisors, whose sum is σ = 656667648. Its totient is φ = 656667646.

The previous prime is 656667617. The next prime is 656667679. The reversal of 656667647 is 746766656.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 656667647 - 2¹² = 656663551 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656667617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328333823 + 328333824.

It is an arithmetic number, because the mean of its divisors is an integer number (328333824).

Almost surely, 2^656667647 is an apocalyptic number.

656667647 is a deficient number, since it is larger than the sum of its proper divisors (1).

656667647 is an equidigital number, since it uses as much as digits as its factorization.

656667647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7620480, while the sum is 53.

The square root of 656667647 is about 25625.5272531123. The cubic root of 656667647 is about 869.1909716009.

Subtracting 656667647 from its reverse (746766656), we obtain a palindrome (90099009).

The spelling of 656667647 in words is "six hundred fifty-six million, six hundred sixty-seven thousand, six hundred forty-seven".