656991623 has 2 divisors, whose sum is σ = 656991624. Its totient is φ = 656991622.

The previous prime is 656991589. The next prime is 656991631. The reversal of 656991623 is 326199656.

656991623 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-656991623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656991653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328495811 + 328495812.

It is an arithmetic number, because the mean of its divisors is an integer number (328495812).

Almost surely, 2^656991623 is an apocalyptic number.

656991623 is a deficient number, since it is larger than the sum of its proper divisors (1).

656991623 is an equidigital number, since it uses as much as digits as its factorization.

656991623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 524880, while the sum is 47.

The square root of 656991623 is about 25631.8478264834. The cubic root of 656991623 is about 869.3338905332. Note that the first 3 decimals are identical.

The spelling of 656991623 in words is "six hundred fifty-six million, nine hundred ninety-one thousand, six hundred twenty-three".