209621020 has 48 divisors (see below), whose sum is σ = 513374400. Its totient is φ = 71867712.

The previous prime is 209621017. The next prime is 209621051. The reversal of 209621020 is 20126902.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 209620982 and 209621000.

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, 8419 + ... + 22138.

It is an arithmetic number, because the mean of its divisors is an integer number (10695300).

Almost surely, 2^209621020 is an apocalyptic number.

209621020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

209621020 is an abundant number, since it is smaller than the sum of its proper divisors (303753380).

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

209621020 is a wasteful number, since it uses less digits than its factorization.

209621020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30587 (or 30571 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 209621020 is about 14478.2947890972. The cubic root of 209621020 is about 594.0344200410.

Adding to 209621020 its reverse (20126902), we get a palindrome (229747922).

The spelling of 209621020 in words is "two hundred nine million, six hundred twenty-one thousand, twenty".