1281860640 has 120 divisors (see below), whose sum is σ = 4523945580. Its totient is φ = 341826048.

The previous prime is 1281860579. The next prime is 1281860719. The reversal of 1281860640 is 460681821.

1281860640 is a `hidden beast` number, since 1 + 2 + 8 + 1 + 8 + 6 + 0 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1252310544 + 29550096 = 35388^2 + 5436^2 .

It is a tau number, because it is divible by the number of its divisors (120).

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 = 1281860595 and 1281860604.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 36495 + ... + 62414.

Almost surely, 2^1281860640 is an apocalyptic number.

1281860640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1281860640 is an abundant number, since it is smaller than the sum of its proper divisors (3242084940).

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

1281860640 is an equidigital number, since it uses as much as digits as its factorization.

1281860640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98936 (or 98919 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 1281860640 is about 35803.0814316310. The cubic root of 1281860640 is about 1086.2928913009.

The spelling of 1281860640 in words is "one billion, two hundred eighty-one million, eight hundred sixty thousand, six hundred forty".