1256121984 has 128 divisors (see below), whose sum is σ = 3709601280. Its totient is φ = 373985280.

The previous prime is 1256121983. The next prime is 1256122003. The reversal of 1256121984 is 4891216521.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (1256121983) 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, 150694 + ... + 158810.

It is an arithmetic number, because the mean of its divisors is an integer number (28981260).

Almost surely, 2^1256121984 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 1256121984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1854800640).

1256121984 is an abundant number, since it is smaller than the sum of its proper divisors (2453479296).

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

1256121984 is a wasteful number, since it uses less digits than its factorization.

1256121984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8178 (or 8166 counting only the distinct ones).

The product of its digits is 34560, while the sum is 39.

The square root of 1256121984 is about 35441.8112403980. The cubic root of 1256121984 is about 1078.9730704818.

The spelling of 1256121984 in words is "one billion, two hundred fifty-six million, one hundred twenty-one thousand, nine hundred eighty-four".