216478861 has 2 divisors, whose sum is σ = 216478862. Its totient is φ = 216478860.

The previous prime is 216478853. The next prime is 216478903. The reversal of 216478861 is 168874612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 124434025 + 92044836 = 11155^2 + 9594^2 .

It is a cyclic number.

It is not a de Polignac number, because 216478861 - 2³ = 216478853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216488861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108239430 + 108239431.

It is an arithmetic number, because the mean of its divisors is an integer number (108239431).

Almost surely, 2^216478861 is an apocalyptic number.

It is an amenable number.

216478861 is a deficient number, since it is larger than the sum of its proper divisors (1).

216478861 is an equidigital number, since it uses as much as digits as its factorization.

216478861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129024, while the sum is 43.

The square root of 216478861 is about 14713.2206195652. The cubic root of 216478861 is about 600.4430625602.

The spelling of 216478861 in words is "two hundred sixteen million, four hundred seventy-eight thousand, eight hundred sixty-one".