1261979545 has 4 divisors (see below), whose sum is σ = 1514375460. Its totient is φ = 1009583632.

The previous prime is 1261979539. The next prime is 1261979561. The reversal of 1261979545 is 5459791621.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 314140176 + 947839369 = 17724^2 + 30787^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261979545 - 2¹⁷ = 1261848473 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126197950 + ... + 126197959.

It is an arithmetic number, because the mean of its divisors is an integer number (378593865).

Almost surely, 2^1261979545 is an apocalyptic number.

It is an amenable number.

1261979545 is a deficient number, since it is larger than the sum of its proper divisors (252395915).

1261979545 is an equidigital number, since it uses as much as digits as its factorization.

1261979545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252395914.

The product of its digits is 680400, while the sum is 49.

The square root of 1261979545 is about 35524.3514367258. The cubic root of 1261979545 is about 1080.6476296851.

The spelling of 1261979545 in words is "one billion, two hundred sixty-one million, nine hundred seventy-nine thousand, five hundred forty-five".