1261812005 has 16 divisors (see below), whose sum is σ = 1538359104. Its totient is φ = 993358080.

The previous prime is 1261811963. The next prime is 1261812017. The reversal of 1261812005 is 5002181621.

It is not a de Polignac number, because 1261812005 - 2²² = 1257617701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 626450 + ... + 628460.

It is an arithmetic number, because the mean of its divisors is an integer number (96147444).

Almost surely, 2^1261812005 is an apocalyptic number.

It is an amenable number.

1261812005 is a deficient number, since it is larger than the sum of its proper divisors (276547099).

1261812005 is a wasteful number, since it uses less digits than its factorization.

1261812005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3956.

The product of its (nonzero) digits is 960, while the sum is 26.

The square root of 1261812005 is about 35521.9932576988. The cubic root of 1261812005 is about 1080.5998054243.

Adding to 1261812005 its reverse (5002181621), we get a palindrome (6263993626).

The spelling of 1261812005 in words is "one billion, two hundred sixty-one million, eight hundred twelve thousand, five".