209490840 has 256 divisors, whose sum is σ = 771724800. Its totient is φ = 50222592.

The previous prime is 209490833. The next prime is 209490851. The reversal of 209490840 is 48094902.

It is a happy number.

209490840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a junction number, because it is equal to n+sod(n) for n = 209490795 and 209490804.

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, 603547 + ... + 603893.

It is an arithmetic number, because the mean of its divisors is an integer number (3014550).

Almost surely, 2^209490840 is an apocalyptic number.

209490840 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 209490840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (385862400).

209490840 is an abundant number, since it is smaller than the sum of its proper divisors (562233960).

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

209490840 is a wasteful number, since it uses less digits than its factorization.

209490840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423 (or 413 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 209490840 is about 14473.7983957218. The cubic root of 209490840 is about 593.9114244009.

The spelling of 209490840 in words is "two hundred nine million, four hundred ninety thousand, eight hundred forty".