1321312728 has 16 divisors (see below), whose sum is σ = 3303281880. Its totient is φ = 440437568.

The previous prime is 1321312697. The next prime is 1321312807. The reversal of 1321312728 is 8272131231.

It is a junction number, because it is equal to n+sod(n) for n = 1321312695 and 1321312704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27527325 + ... + 27527372.

Almost surely, 2^1321312728 is an apocalyptic number.

It is an amenable number.

1321312728 is an abundant number, since it is smaller than the sum of its proper divisors (1981969152).

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

1321312728 is a wasteful number, since it uses less digits than its factorization.

1321312728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55054706 (or 55054702 counting only the distinct ones).

The product of its digits is 4032, while the sum is 30.

The square root of 1321312728 is about 36349.8655843457. The cubic root of 1321312728 is about 1097.3248293580.

Adding to 1321312728 its reverse (8272131231), we get a palindrome (9593443959).

The spelling of 1321312728 in words is "one billion, three hundred twenty-one million, three hundred twelve thousand, seven hundred twenty-eight".