1261994783 has 4 divisors (see below), whose sum is σ = 1442279760. Its totient is φ = 1081709808.

The previous prime is 1261994759. The next prime is 1261994849. The reversal of 1261994783 is 3874991621.

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

It is a cyclic number.

It is not a de Polignac number, because 1261994783 - 2²⁸ = 993559327 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261994753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90142478 + ... + 90142491.

It is an arithmetic number, because the mean of its divisors is an integer number (360569940).

Almost surely, 2^1261994783 is an apocalyptic number.

1261994783 is a deficient number, since it is larger than the sum of its proper divisors (180284977).

1261994783 is an equidigital number, since it uses as much as digits as its factorization.

1261994783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180284976.

The product of its digits is 653184, while the sum is 50.

The square root of 1261994783 is about 35524.5659086779. The cubic root of 1261994783 is about 1080.6519791592.

The spelling of 1261994783 in words is "one billion, two hundred sixty-one million, nine hundred ninety-four thousand, seven hundred eighty-three".