1261457640 has 96 divisors (see below), whose sum is σ = 4129823880. Its totient is φ = 333920256.

The previous prime is 1261457623. The next prime is 1261457641. The reversal of 1261457640 is 467541621.

1261457640 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 4 + 5 + 7 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 724794084 + 536663556 = 26922^2 + 23166^2 .

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 = 1261457595 and 1261457604.

It is not an unprimeable number, because it can be changed into a prime (1261457641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36532 + ... + 62108.

Almost surely, 2^1261457640 is an apocalyptic number.

1261457640 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 1261457640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2064911940).

1261457640 is an abundant number, since it is smaller than the sum of its proper divisors (2868366240).

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

1261457640 is a wasteful number, since it uses less digits than its factorization.

1261457640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25731 (or 25724 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 1261457640 is about 35517.0049412954. The cubic root of 1261457640 is about 1080.4986380552.

The spelling of 1261457640 in words is "one billion, two hundred sixty-one million, four hundred fifty-seven thousand, six hundred forty".