209709381971716 has 81 divisors (see below), whose sum is σ = 405057949591477. Its totient is φ = 94929277806880.

The previous prime is 209709381971689. The next prime is 209709381971723. The reversal of 209709381971716 is 617179183907902.

The square root of 209709381971716 is 14481346.

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

It can be written as a sum of positive squares in only one way, i.e., 13797851986116 + 195911529985600 = 3714546^2 + 13996840^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 85700604405 + ... + 85700606851.

Almost surely, 2^{209709381971716} is an apocalyptic number.

209709381971716 is the 14481346-th square number.

It is an amenable number.

209709381971716 is a deficient number, since it is larger than the sum of its proper divisors (195348567619761).

209709381971716 is an frugal number, since it uses more digits than its factorization.

209709381971716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5458 (or 2729 counting only the distinct ones).

The product of its (nonzero) digits is 72013536, while the sum is 70.

The spelling of 209709381971716 in words is "two hundred nine trillion, seven hundred nine billion, three hundred eighty-one million, nine hundred seventy-one thousand, seven hundred sixteen".