216387961 has 2 divisors, whose sum is σ = 216387962. Its totient is φ = 216387960.

The previous prime is 216387947. The next prime is 216387989. The reversal of 216387961 is 169783612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 205205625 + 11182336 = 14325^2 + 3344^2 .

It is a cyclic number.

It is not a de Polignac number, because 216387961 - 2¹¹ = 216385913 is a prime.

It is not a weakly prime, because it can be changed into another prime (216387901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108193980 + 108193981.

It is an arithmetic number, because the mean of its divisors is an integer number (108193981).

Almost surely, 2^216387961 is an apocalyptic number.

It is an amenable number.

216387961 is a deficient number, since it is larger than the sum of its proper divisors (1).

216387961 is an equidigital number, since it uses as much as digits as its factorization.

216387961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The square root of 216387961 is about 14710.1312366681. The cubic root of 216387961 is about 600.3590082937.

The spelling of 216387961 in words is "two hundred sixteen million, three hundred eighty-seven thousand, nine hundred sixty-one".