209891968 has 64 divisors (see below), whose sum is σ = 491289120. Its totient is φ = 88058880.

The previous prime is 209891959. The next prime is 209891971. The reversal of 209891968 is 869198902.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (52).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12571 + ... + 24037.

Almost surely, 2^209891968 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209891968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (245644560).

209891968 is an abundant number, since it is smaller than the sum of its proper divisors (281397152).

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

209891968 is a wasteful number, since it uses less digits than its factorization.

209891968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11505 (or 11493 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 52.

The square root of 209891968 is about 14487.6488085541. The cubic root of 209891968 is about 594.2902517969.

The spelling of 209891968 in words is "two hundred nine million, eight hundred ninety-one thousand, nine hundred sixty-eight".