1261232640 has 320 divisors, whose sum is σ = 4560779520. Its totient is φ = 330301440.

The previous prime is 1261232633. The next prime is 1261232659. The reversal of 1261232640 is 462321621.

1261232640 is a `hidden beast` number, since 1 + 2 + 6 + 12 + 3 + 2 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4907392 + ... + 4907648.

It is an arithmetic number, because the mean of its divisors is an integer number (14252436).

Almost surely, 2^1261232640 is an apocalyptic number.

1261232640 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 1261232640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2280389760).

1261232640 is an abundant number, since it is smaller than the sum of its proper divisors (3299546880).

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

1261232640 is an equidigital number, since it uses as much as digits as its factorization.

1261232640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 1261232640 is about 35513.8373032259. The cubic root of 1261232640 is about 1080.4343931580.

The spelling of 1261232640 in words is "one billion, two hundred sixty-one million, two hundred thirty-two thousand, six hundred forty".