1280400840 has 48 divisors (see below), whose sum is σ = 4161303900. Its totient is φ = 341440128.

The previous prime is 1280400839. The next prime is 1280400851. The reversal of 1280400840 is 480040821.

It can be written as a sum of positive squares in 2 ways, for example, as 1256135364 + 24265476 = 35442^2 + 4926^2 .

It is a super-2 number, since 2×1280400840² = 3278852622145411200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1777975 + ... + 1778694.

Almost surely, 2^1280400840 is an apocalyptic number.

1280400840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1280400840 is an abundant number, since it is smaller than the sum of its proper divisors (2880903060).

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

1280400840 is a wasteful number, since it uses less digits than its factorization.

1280400840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3556686 (or 3556679 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 1280400840 is about 35782.6891107977. The cubic root of 1280400840 is about 1085.8803730547.

The spelling of 1280400840 in words is "one billion, two hundred eighty million, four hundred thousand, eight hundred forty".