209890540 has 24 divisors (see below), whose sum is σ = 445318272. Its totient is φ = 83089920.

The previous prime is 209890537. The next prime is 209890543. The reversal of 209890540 is 45098902.

It is an interprime number because it is at equal distance from previous prime (209890537) and next prime (209890543).

It is a self number, because there is not a number n which added to its sum of digits gives 209890540.

It is not an unprimeable number, because it can be changed into a prime (209890543) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 52156 + ... + 56035.

It is an arithmetic number, because the mean of its divisors is an integer number (18554928).

Almost surely, 2^209890540 is an apocalyptic number.

209890540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

209890540 is an abundant number, since it is smaller than the sum of its proper divisors (235427732).

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

209890540 is a wasteful number, since it uses less digits than its factorization.

209890540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108297 (or 108295 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 209890540 is about 14487.5995251111. The cubic root of 209890540 is about 594.2889040426.

The spelling of 209890540 in words is "two hundred nine million, eight hundred ninety thousand, five hundred forty".