261219989 has 2 divisors, whose sum is σ = 261219990. Its totient is φ = 261219988.

The previous prime is 261219949. The next prime is 261219997. The reversal of 261219989 is 989912162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 201157489 + 60062500 = 14183^2 + 7750^2 .

It is a cyclic number.

It is not a de Polignac number, because 261219989 - 2²⁴ = 244442773 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 (261219949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130609994 + 130609995.

It is an arithmetic number, because the mean of its divisors is an integer number (130609995).

Almost surely, 2^261219989 is an apocalyptic number.

It is an amenable number.

261219989 is a deficient number, since it is larger than the sum of its proper divisors (1).

261219989 is an equidigital number, since it uses as much as digits as its factorization.

261219989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 139968, while the sum is 47.

The square root of 261219989 is about 16162.3014759656. The cubic root of 261219989 is about 639.2471526781.

The spelling of 261219989 in words is "two hundred sixty-one million, two hundred nineteen thousand, nine hundred eighty-nine".