1978123556 has 54 divisors (see below), whose sum is σ = 3731744646. Its totient is φ = 916872000.

The previous prime is 1978123531. The next prime is 1978123571. The reversal of 1978123556 is 6553218791.

It can be written as a sum of positive squares in only one way, i.e., 1206172900 + 771950656 = 34730^2 + 27784^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1978123556.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 13100081 + ... + 13100231.

Almost surely, 2^1978123556 is an apocalyptic number.

It is an amenable number.

1978123556 is a deficient number, since it is larger than the sum of its proper divisors (1753621090).

1978123556 is a wasteful number, since it uses less digits than its factorization.

1978123556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 393 (or 217 counting only the distinct ones).

The product of its digits is 453600, while the sum is 47.

The square root of 1978123556 is about 44476.1009532086. The cubic root of 1978123556 is about 1255.3104327746.

The spelling of 1978123556 in words is "one billion, nine hundred seventy-eight million, one hundred twenty-three thousand, five hundred fifty-six".