1978561728 has 560 divisors, whose sum is σ = 7342229664. Its totient is φ = 517570560.

The previous prime is 1978561703. The next prime is 1978561747. The reversal of 1978561728 is 8271658791.

1978561728 is a `hidden beast` number, since 1 + 9 + 7 + 8 + 561 + 72 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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 79 ways as a sum of consecutive naturals, for example, 12602226 + ... + 12602382.

Almost surely, 2^1978561728 is an apocalyptic number.

1978561728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1978561728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3671114832).

1978561728 is an abundant number, since it is smaller than the sum of its proper divisors (5363667936).

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

1978561728 is a wasteful number, since it uses less digits than its factorization.

1978561728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222 (or 203 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 54.

The square root of 1978561728 is about 44481.0266068579. The cubic root of 1978561728 is about 1255.4031134152.

The spelling of 1978561728 in words is "one billion, nine hundred seventy-eight million, five hundred sixty-one thousand, seven hundred twenty-eight".