1256121980 has 12 divisors (see below), whose sum is σ = 2637856200. Its totient is φ = 502448784.

The previous prime is 1256121949. The next prime is 1256121983. The reversal of 1256121980 is 891216521.

It is a self number, because there is not a number n which added to its sum of digits gives 1256121980.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256121983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31403030 + ... + 31403069.

It is an arithmetic number, because the mean of its divisors is an integer number (219821350).

Almost surely, 2^1256121980 is an apocalyptic number.

1256121980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1256121980 is an abundant number, since it is smaller than the sum of its proper divisors (1381734220).

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

1256121980 is a wasteful number, since it uses less digits than its factorization.

1256121980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62806108 (or 62806106 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 1256121980 is about 35441.8111839674. The cubic root of 1256121980 is about 1078.9730693365.

The spelling of 1256121980 in words is "one billion, two hundred fifty-six million, one hundred twenty-one thousand, nine hundred eighty".