1261538063 has 4 divisors (see below), whose sum is σ = 1316387568. Its totient is φ = 1206688560.

The previous prime is 1261538029. The next prime is 1261538071. The reversal of 1261538063 is 3608351621.

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

It is not a de Polignac number, because 1261538063 - 2²⁶ = 1194429199 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 (1261538093) 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, 27424718 + ... + 27424763.

It is an arithmetic number, because the mean of its divisors is an integer number (329096892).

Almost surely, 2^1261538063 is an apocalyptic number.

1261538063 is a deficient number, since it is larger than the sum of its proper divisors (54849505).

1261538063 is an equidigital number, since it uses as much as digits as its factorization.

1261538063 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54849504.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 1261538063 is about 35518.1370992342. The cubic root of 1261538063 is about 1080.5215996124.

Adding to 1261538063 its reverse (3608351621), we get a palindrome (4869889684).

The spelling of 1261538063 in words is "one billion, two hundred sixty-one million, five hundred thirty-eight thousand, sixty-three".