216399641 has 2 divisors, whose sum is σ = 216399642. Its totient is φ = 216399640.

The previous prime is 216399637. The next prime is 216399661. The reversal of 216399641 is 146993612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 158030041 + 58369600 = 12571^2 + 7640^2 .

It is a cyclic number.

It is not a de Polignac number, because 216399641 - 2² = 216399637 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (216399661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108199820 + 108199821.

It is an arithmetic number, because the mean of its divisors is an integer number (108199821).

Almost surely, 2^216399641 is an apocalyptic number.

It is an amenable number.

216399641 is a deficient number, since it is larger than the sum of its proper divisors (1).

216399641 is an equidigital number, since it uses as much as digits as its factorization.

216399641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 41.

The square root of 216399641 is about 14710.5282366066. The cubic root of 216399641 is about 600.3698099838.

The spelling of 216399641 in words is "two hundred sixteen million, three hundred ninety-nine thousand, six hundred forty-one".