209323505664 has 768 divisors, whose sum is σ = 808380518400. Its totient is φ = 51937542144.

The previous prime is 209323505627. The next prime is 209323505683. The reversal of 209323505664 is 466505323902.

209323505664 is a `hidden beast` number, since 2 + 0 + 9 + 32 + 3 + 50 + 566 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (768).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 85541689 + ... + 85544135.

It is an arithmetic number, because the mean of its divisors is an integer number (1052578800).

Almost surely, 2^209323505664 is an apocalyptic number.

209323505664 is a gapful number since it is divisible by the number (24) 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 209323505664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (404190259200).

209323505664 is an abundant number, since it is smaller than the sum of its proper divisors (599057012736).

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

209323505664 is a wasteful number, since it uses less digits than its factorization.

209323505664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2515 (or 2489 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 45.

The spelling of 209323505664 in words is "two hundred nine billion, three hundred twenty-three million, five hundred five thousand, six hundred sixty-four".