215688643 has 2 divisors, whose sum is σ = 215688644. Its totient is φ = 215688642.

The previous prime is 215688623. The next prime is 215688679. The reversal of 215688643 is 346886512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215688643 is a prime.

It is equal to p_11898178 and since 215688643 and 11898178 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 215688643.

It is not a weakly prime, because it can be changed into another prime (215688623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107844321 + 107844322.

It is an arithmetic number, because the mean of its divisors is an integer number (107844322).

Almost surely, 2^215688643 is an apocalyptic number.

215688643 is a deficient number, since it is larger than the sum of its proper divisors (1).

215688643 is an equidigital number, since it uses as much as digits as its factorization.

215688643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 276480, while the sum is 43.

The square root of 215688643 is about 14686.3420564823. The cubic root of 215688643 is about 599.7115678485.

The spelling of 215688643 in words is "two hundred fifteen million, six hundred eighty-eight thousand, six hundred forty-three".