1978208640 has 192 divisors, whose sum is σ = 6947974800. Its totient is φ = 518492160.

The previous prime is 1978208629. The next prime is 1978208641. The reversal of 1978208640 is 468028791.

1978208640 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978208641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 336930 + ... + 342750.

Almost surely, 2^1978208640 is an apocalyptic number.

1978208640 is a gapful number since it is divisible by the number (10) 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 1978208640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3473987400).

1978208640 is an abundant number, since it is smaller than the sum of its proper divisors (4969766160).

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

1978208640 is a wasteful number, since it uses less digits than its factorization.

1978208640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5905 (or 5890 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 1978208640 is about 44477.0574566259. The cubic root of 1978208640 is about 1255.3284305216.

The spelling of 1978208640 in words is "one billion, nine hundred seventy-eight million, two hundred eight thousand, six hundred forty".