216561743 has 2 divisors, whose sum is σ = 216561744. Its totient is φ = 216561742.

The previous prime is 216561739. The next prime is 216561769. The reversal of 216561743 is 347165612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216561743 - 2² = 216561739 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216561343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108280871 + 108280872.

It is an arithmetic number, because the mean of its divisors is an integer number (108280872).

Almost surely, 2^216561743 is an apocalyptic number.

216561743 is a deficient number, since it is larger than the sum of its proper divisors (1).

216561743 is an equidigital number, since it uses as much as digits as its factorization.

216561743 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 35.

The square root of 216561743 is about 14716.0369325440. The cubic root of 216561743 is about 600.5196821615.

The spelling of 216561743 in words is "two hundred sixteen million, five hundred sixty-one thousand, seven hundred forty-three".