1261245440 has 176 divisors, whose sum is σ = 3725081472. Its totient is φ = 399015936.

The previous prime is 1261245439. The next prime is 1261245443. The reversal of 1261245440 is 445421621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261245443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 464567 + ... + 467273.

Almost surely, 2^1261245440 is an apocalyptic number.

1261245440 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 1261245440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1862540736).

1261245440 is an abundant number, since it is smaller than the sum of its proper divisors (2463836032).

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

1261245440 is a wasteful number, since it uses less digits than its factorization.

1261245440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2752 (or 2734 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 29.

The square root of 1261245440 is about 35514.0175142154. The cubic root of 1261245440 is about 1080.4380481838.

The spelling of 1261245440 in words is "one billion, two hundred sixty-one million, two hundred forty-five thousand, four hundred forty".