1265121726 has 64 divisors (see below), whose sum is σ = 2911334400. Its totient is φ = 362469600.

The previous prime is 1265121709. The next prime is 1265121727. The reversal of 1265121726 is 6271215621.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265121727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1217115 + ... + 1218153.

It is an arithmetic number, because the mean of its divisors is an integer number (45489600).

Almost surely, 2^1265121726 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1265121726, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1455667200).

1265121726 is an abundant number, since it is smaller than the sum of its proper divisors (1646212674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1265121726 is a wasteful number, since it uses less digits than its factorization.

1265121726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2045.

The product of its digits is 10080, while the sum is 33.

The square root of 1265121726 is about 35568.5496752398. The cubic root of 1265121726 is about 1081.5437815938.

The spelling of 1265121726 in words is "one billion, two hundred sixty-five million, one hundred twenty-one thousand, seven hundred twenty-six".