219781649 has 2 divisors, whose sum is σ = 219781650. Its totient is φ = 219781648.

The previous prime is 219781613. The next prime is 219781651. The reversal of 219781649 is 946187912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219780625 + 1024 = 14825^2 + 32^2 .

It is a cyclic number.

It is not a de Polignac number, because 219781649 - 2¹² = 219777553 is a prime.

Together with 219781651, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (219781699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109890824 + 109890825.

It is an arithmetic number, because the mean of its divisors is an integer number (109890825).

Almost surely, 2^219781649 is an apocalyptic number.

It is an amenable number.

219781649 is a deficient number, since it is larger than the sum of its proper divisors (1).

219781649 is an equidigital number, since it uses as much as digits as its factorization.

219781649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 47.

The square root of 219781649 is about 14825.0345362161. The cubic root of 219781649 is about 603.4812888328.

The spelling of 219781649 in words is "two hundred nineteen million, seven hundred eighty-one thousand, six hundred forty-nine".