209243664 has 240 divisors, whose sum is σ = 705204864. Its totient is φ = 56678400.

The previous prime is 209243659. The next prime is 209243681. The reversal of 209243664 is 466342902.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2520967 + ... + 2521049.

Almost surely, 2^209243664 is an apocalyptic number.

209243664 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 209243664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (352602432).

209243664 is an abundant number, since it is smaller than the sum of its proper divisors (495961200).

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

209243664 is a wasteful number, since it uses less digits than its factorization.

209243664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The square root of 209243664 is about 14465.2571356336. The cubic root of 209243664 is about 593.6777492288.

The spelling of 209243664 in words is "two hundred nine million, two hundred forty-three thousand, six hundred sixty-four".