1265136840 has 256 divisors, whose sum is σ = 4647456000. Its totient is φ = 303575040.

The previous prime is 1265136773. The next prime is 1265136881. The reversal of 1265136840 is 486315621.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1265136795 and 1265136804.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1294432 + ... + 1295408.

It is an arithmetic number, because the mean of its divisors is an integer number (18154125).

Almost surely, 2^1265136840 is an apocalyptic number.

1265136840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1265136840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2323728000).

1265136840 is an abundant number, since it is smaller than the sum of its proper divisors (3382319160).

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

1265136840 is a wasteful number, since it uses less digits than its factorization.

1265136840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117 (or 1107 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 1265136840 is about 35568.7621375836. The cubic root of 1265136840 is about 1081.5480885279.

The spelling of 1265136840 in words is "one billion, two hundred sixty-five million, one hundred thirty-six thousand, eight hundred forty".