201691409 has 2 divisors, whose sum is σ = 201691410. Its totient is φ = 201691408.

The previous prime is 201691379. The next prime is 201691453. The reversal of 201691409 is 904196102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 195300625 + 6390784 = 13975^2 + 2528^2 .

It is a cyclic number.

It is not a de Polignac number, because 201691409 - 2¹⁶ = 201625873 is a prime.

It is not a weakly prime, because it can be changed into another prime (201691459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100845704 + 100845705.

It is an arithmetic number, because the mean of its divisors is an integer number (100845705).

Almost surely, 2^201691409 is an apocalyptic number.

It is an amenable number.

201691409 is a deficient number, since it is larger than the sum of its proper divisors (1).

201691409 is an equidigital number, since it uses as much as digits as its factorization.

201691409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 201691409 is about 14201.8100606930. The cubic root of 201691409 is about 586.4474919845.

The spelling of 201691409 in words is "two hundred one million, six hundred ninety-one thousand, four hundred nine".