209138838489 has 225 divisors, whose sum is σ = 393616409901. Its totient is φ = 110634128640.

The previous prime is 209138838481. The next prime is 209138838499. The reversal of 209138838489 is 984838831902.

The square root of 209138838489 is 457317.

It is a perfect power (a square), and thus also a powerful number.

209138838489 is a `hidden beast` number, since 2 + 0 + 91 + 38 + 8 + 38 + 489 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 19297377225 + 189841461264 = 138915^2 + 435708^2 .

It is not a de Polignac number, because 209138838489 - 2³ = 209138838481 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (209138838481) by changing a digit.

It is a polite number, since it can be written in 224 ways as a sum of consecutive naturals, for example, 3428505519 + ... + 3428505579.

Almost surely, 2^209138838489 is an apocalyptic number.

209138838489 is the 457317-th square number.

209138838489 is the 228659-th centered octagonal number.

It is an amenable number.

209138838489 is a deficient number, since it is larger than the sum of its proper divisors (184477571412).

209138838489 is an frugal number, since it uses more digits than its factorization.

209138838489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196 (or 88 counting only the distinct ones).

The product of its (nonzero) digits is 23887872, while the sum is 63.

The spelling of 209138838489 in words is "two hundred nine billion, one hundred thirty-eight million, eight hundred thirty-eight thousand, four hundred eighty-nine".