261219997 has 2 divisors, whose sum is σ = 261219998. Its totient is φ = 261219996.

The previous prime is 261219989. The next prime is 261220009. The reversal of 261219997 is 799912162.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 215913636 + 45306361 = 14694^2 + 6731^2 .

It is a cyclic number.

It is not a de Polignac number, because 261219997 - 2³ = 261219989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261219197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130609998 + 130609999.

It is an arithmetic number, because the mean of its divisors is an integer number (130609999).

Almost surely, 2^261219997 is an apocalyptic number.

It is an amenable number.

261219997 is a deficient number, since it is larger than the sum of its proper divisors (1).

261219997 is an equidigital number, since it uses as much as digits as its factorization.

261219997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 46.

The square root of 261219997 is about 16162.3017234551. The cubic root of 261219997 is about 639.2471592039.

The spelling of 261219997 in words is "two hundred sixty-one million, two hundred nineteen thousand, nine hundred ninety-seven".