209638540 has 24 divisors (see below), whose sum is σ = 442461600. Its totient is φ = 83432448.

The previous prime is 209638531. The next prime is 209638567. The reversal of 209638540 is 45836902.

It is a self number, because there is not a number n which added to its sum of digits gives 209638540.

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, 22357 + ... + 30316.

It is an arithmetic number, because the mean of its divisors is an integer number (18435900).

Almost surely, 2^209638540 is an apocalyptic number.

209638540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

209638540 is an abundant number, since it is smaller than the sum of its proper divisors (232823060).

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

209638540 is a wasteful number, since it uses less digits than its factorization.

209638540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52881 (or 52879 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 209638540 is about 14478.8998200830. The cubic root of 209638540 is about 594.0509692610.

The spelling of 209638540 in words is "two hundred nine million, six hundred thirty-eight thousand, five hundred forty".