209978081280 has 720 divisors, whose sum is σ = 841337025984. Its totient is φ = 47877980160.

The previous prime is 209978081233. The next prime is 209978081281. The reversal of 209978081280 is 82180879902.

209978081280 is a `hidden beast` number, since 209 + 9 + 7 + 80 + 81 + 280 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209978081281) 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 47 ways as a sum of consecutive naturals, for example, 137870599 + ... + 137872121.

Almost surely, 2^209978081280 is an apocalyptic number.

209978081280 is a gapful number since it is divisible by the number (20) 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 209978081280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (420668512992).

209978081280 is an abundant number, since it is smaller than the sum of its proper divisors (631358944704).

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

209978081280 is a wasteful number, since it uses less digits than its factorization.

209978081280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1590 (or 1561 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 54.

The spelling of 209978081280 in words is "two hundred nine billion, nine hundred seventy-eight million, eighty-one thousand, two hundred eighty".