209809232640 has 1296 divisors, whose sum is σ = 892140657408. Its totient is φ = 46276780032.

The previous prime is 209809232617. The next prime is 209809232641. The reversal of 209809232640 is 46232908902.

209809232640 is a `hidden beast` number, since 209 + 80 + 9 + 2 + 326 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (1296).

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 (209809232641) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 2527822039 + ... + 2527822121.

Almost surely, 2^209809232640 is an apocalyptic number.

209809232640 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 209809232640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (446070328704).

209809232640 is an abundant number, since it is smaller than the sum of its proper divisors (682331424768).

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

209809232640 is an frugal number, since it uses more digits than its factorization.

209809232640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178 (or 143 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 209809232640 in words is "two hundred nine billion, eight hundred nine million, two hundred thirty-two thousand, six hundred forty".