209471408640 has 640 divisors, whose sum is σ = 808778234880. Its totient is φ = 51081117696.

The previous prime is 209471408617. The next prime is 209471408647. The reversal of 209471408640 is 46804174902.

209471408640 is a `hidden beast` number, since 20 + 9 + 471 + 40 + 86 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

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

It is not an unprimeable number, because it can be changed into a prime (209471408647) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 101536249 + ... + 101538311.

It is an arithmetic number, because the mean of its divisors is an integer number (1263715992).

Almost surely, 2^209471408640 is an apocalyptic number.

209471408640 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 209471408640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (404389117440).

209471408640 is an abundant number, since it is smaller than the sum of its proper divisors (599306826240).

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

209471408640 is a wasteful number, since it uses less digits than its factorization.

209471408640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2221 (or 2199 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 209471408640 in words is "two hundred nine billion, four hundred seventy-one million, four hundred eight thousand, six hundred forty".