219981997 has 2 divisors, whose sum is σ = 219981998. Its totient is φ = 219981996.

The previous prime is 219981991. The next prime is 219982001. The reversal of 219981997 is 799189912.

219981997 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., 178649956 + 41332041 = 13366^2 + 6429^2 .

It is a cyclic number.

It is not a de Polignac number, because 219981997 - 2⁷ = 219981869 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (219981991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109990998 + 109990999.

It is an arithmetic number, because the mean of its divisors is an integer number (109990999).

Almost surely, 2^219981997 is an apocalyptic number.

It is an amenable number.

219981997 is a deficient number, since it is larger than the sum of its proper divisors (1).

219981997 is an equidigital number, since it uses as much as digits as its factorization.

219981997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 734832, while the sum is 55.

The square root of 219981997 is about 14831.7900807691. The cubic root of 219981997 is about 603.6646064573.

The spelling of 219981997 in words is "two hundred nineteen million, nine hundred eighty-one thousand, nine hundred ninety-seven".