1261798989 has 32 divisors (see below), whose sum is σ = 1893943296. Its totient is φ = 740651520.

The previous prime is 1261798897. The next prime is 1261798991. The reversal of 1261798989 is 9898971621.

It is not a de Polignac number, because 1261798989 - 2¹⁵ = 1261766221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261798289) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 146254 + ... + 154640.

It is an arithmetic number, because the mean of its divisors is an integer number (59185728).

Almost surely, 2^1261798989 is an apocalyptic number.

It is an amenable number.

1261798989 is a deficient number, since it is larger than the sum of its proper divisors (632144307).

1261798989 is a wasteful number, since it uses less digits than its factorization.

1261798989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8545.

The product of its digits is 3919104, while the sum is 60.

The square root of 1261798989 is about 35521.8100467867. The cubic root of 1261798989 is about 1080.5960898324.

The spelling of 1261798989 in words is "one billion, two hundred sixty-one million, seven hundred ninety-eight thousand, nine hundred eighty-nine".