1231909728 has 96 divisors (see below), whose sum is σ = 3728664576. Its totient is φ = 348837888.

The previous prime is 1231909717. The next prime is 1231909729. The reversal of 1231909728 is 8279091321.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 1231909728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231909729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67825 + ... + 84047.

It is an arithmetic number, because the mean of its divisors is an integer number (38840256).

Almost surely, 2^1231909728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1231909728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1864332288).

1231909728 is an abundant number, since it is smaller than the sum of its proper divisors (2496754848).

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

1231909728 is a wasteful number, since it uses less digits than its factorization.

1231909728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16356 (or 16348 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 1231909728 is about 35098.5715948669. The cubic root of 1231909728 is about 1071.9954982361.

The spelling of 1231909728 in words is "one billion, two hundred thirty-one million, nine hundred nine thousand, seven hundred twenty-eight".