209871740 has 48 divisors (see below), whose sum is σ = 481360320. Its totient is φ = 76392960.

The previous prime is 209871737. The next prime is 209871751. The reversal of 209871740 is 47178902.

It is a super-2 number, since 2×209871740² = 88092294501255200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 209871694 and 209871703.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12776 + ... + 24144.

It is an arithmetic number, because the mean of its divisors is an integer number (10028340).

Almost surely, 2^209871740 is an apocalyptic number.

209871740 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 209871740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (240680160).

209871740 is an abundant number, since it is smaller than the sum of its proper divisors (271488580).

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

209871740 is a wasteful number, since it uses less digits than its factorization.

209871740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11462 (or 11460 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 209871740 is about 14486.9506798360. The cubic root of 209871740 is about 594.2711599286.

The spelling of 209871740 in words is "two hundred nine million, eight hundred seventy-one thousand, seven hundred forty".