1261979549 has 8 divisors (see below), whose sum is σ = 1293236280. Its totient is φ = 1230745600.

The previous prime is 1261979539. The next prime is 1261979561. The reversal of 1261979549 is 9459791621.

It can be written as a sum of positive squares in 4 ways, for example, as 6340324 + 1255639225 = 2518^2 + 35435^2 .

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 1261979549 - 2⁴ = 1261979533 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 1261979549.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261979539) 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, 180287 + ... + 187155.

It is an arithmetic number, because the mean of its divisors is an integer number (161654535).

Almost surely, 2^1261979549 is an apocalyptic number.

It is an amenable number.

1261979549 is a deficient number, since it is larger than the sum of its proper divisors (31256731).

1261979549 is an equidigital number, since it uses as much as digits as its factorization.

1261979549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11391.

The product of its digits is 1224720, while the sum is 53.

The square root of 1261979549 is about 35524.3514930252. The cubic root of 1261979549 is about 1080.6476308268.

The spelling of 1261979549 in words is "one billion, two hundred sixty-one million, nine hundred seventy-nine thousand, five hundred forty-nine".