1280385644 has 24 divisors (see below), whose sum is σ = 2269233120. Its totient is φ = 632065536.

The previous prime is 1280385637. The next prime is 1280385649. The reversal of 1280385644 is 4465830821.

It is a super-2 number, since 2×1280385644² = 3278774794722589472, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1280385649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 166574 + ... + 174090.

It is an arithmetic number, because the mean of its divisors is an integer number (94551380).

Almost surely, 2^1280385644 is an apocalyptic number.

It is an amenable number.

1280385644 is a deficient number, since it is larger than the sum of its proper divisors (988847476).

1280385644 is a wasteful number, since it uses less digits than its factorization.

1280385644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8057 (or 8055 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 41.

The square root of 1280385644 is about 35782.4767728563. The cubic root of 1280385644 is about 1085.8760772376.

The spelling of 1280385644 in words is "one billion, two hundred eighty million, three hundred eighty-five thousand, six hundred forty-four".