209713649 has 8 divisors (see below), whose sum is σ = 224016840. Its totient is φ = 195629056.

The previous prime is 209713643. The next prime is 209713661. The reversal of 209713649 is 946317902.

It can be written as a sum of positive squares in 4 ways, for example, as 390625 + 209323024 = 625^2 + 14468^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209713649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209713643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52664 + ... + 56505.

It is an arithmetic number, because the mean of its divisors is an integer number (28002105).

Almost surely, 2^209713649 is an apocalyptic number.

It is an amenable number.

209713649 is a deficient number, since it is larger than the sum of its proper divisors (14303191).

209713649 is a wasteful number, since it uses less digits than its factorization.

209713649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109299.

The product of its (nonzero) digits is 81648, while the sum is 41.

The square root of 209713649 is about 14481.4933276924. The cubic root of 209713649 is about 594.1219060373.

The spelling of 209713649 in words is "two hundred nine million, seven hundred thirteen thousand, six hundred forty-nine".