215720161 has 2 divisors, whose sum is σ = 215720162. Its totient is φ = 215720160.

The previous prime is 215720149. The next prime is 215720171. The reversal of 215720161 is 161027512.

215720161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114597025 + 101123136 = 10705^2 + 10056^2 .

It is a cyclic number.

It is not a de Polignac number, because 215720161 - 2⁹ = 215719649 is a prime.

It is not a weakly prime, because it can be changed into another prime (215720171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107860080 + 107860081.

It is an arithmetic number, because the mean of its divisors is an integer number (107860081).

Almost surely, 2^215720161 is an apocalyptic number.

It is an amenable number.

215720161 is a deficient number, since it is larger than the sum of its proper divisors (1).

215720161 is an equidigital number, since it uses as much as digits as its factorization.

215720161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 215720161 is about 14687.4150550735. The cubic root of 215720161 is about 599.7407778374.

Adding to 215720161 its reverse (161027512), we get a palindrome (376747673).

The spelling of 215720161 in words is "two hundred fifteen million, seven hundred twenty thousand, one hundred sixty-one".