216986779 has 2 divisors, whose sum is σ = 216986780. Its totient is φ = 216986778.

The previous prime is 216986771. The next prime is 216986789. The reversal of 216986779 is 977689612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216986779 - 2³ = 216986771 is a prime.

It is not a weakly prime, because it can be changed into another prime (216986771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108493389 + 108493390.

It is an arithmetic number, because the mean of its divisors is an integer number (108493390).

Almost surely, 2^216986779 is an apocalyptic number.

216986779 is a deficient number, since it is larger than the sum of its proper divisors (1).

216986779 is an equidigital number, since it uses as much as digits as its factorization.

216986779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2286144, while the sum is 55.

The square root of 216986779 is about 14730.4711058404. The cubic root of 216986779 is about 600.9122964150.

The spelling of 216986779 in words is "two hundred sixteen million, nine hundred eighty-six thousand, seven hundred seventy-nine".