217998061 has 2 divisors, whose sum is σ = 217998062. Its totient is φ = 217998060.

The previous prime is 217998059. The next prime is 217998073. The reversal of 217998061 is 160899712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 207532836 + 10465225 = 14406^2 + 3235^2 .

It is a cyclic number.

It is not a de Polignac number, because 217998061 - 2¹ = 217998059 is a prime.

Together with 217998059, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 217997999 and 217998017.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217995061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108999030 + 108999031.

It is an arithmetic number, because the mean of its divisors is an integer number (108999031).

Almost surely, 2^217998061 is an apocalyptic number.

It is an amenable number.

217998061 is a deficient number, since it is larger than the sum of its proper divisors (1).

217998061 is an equidigital number, since it uses as much as digits as its factorization.

217998061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 43.

The square root of 217998061 is about 14764.7573972619. The cubic root of 217998061 is about 601.8443811027.

The spelling of 217998061 in words is "two hundred seventeen million, nine hundred ninety-eight thousand, sixty-one".