1261984139 has 8 divisors (see below), whose sum is σ = 1360004352. Its totient is φ = 1164098880.

The previous prime is 1261984121. The next prime is 1261984147. The reversal of 1261984139 is 9314891621.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1261984139 - 2⁸ = 1261983883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1261984139.

It is not an unprimeable number, because it can be changed into a prime (1261984159) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13874 + ... + 52119.

It is an arithmetic number, because the mean of its divisors is an integer number (170000544).

Almost surely, 2^1261984139 is an apocalyptic number.

1261984139 is a deficient number, since it is larger than the sum of its proper divisors (98020213).

1261984139 is a wasteful number, since it uses less digits than its factorization.

1261984139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67477.

The product of its digits is 93312, while the sum is 44.

The square root of 1261984139 is about 35524.4160965384. The cubic root of 1261984139 is about 1080.6489409818.

The spelling of 1261984139 in words is "one billion, two hundred sixty-one million, nine hundred eighty-four thousand, one hundred thirty-nine".