213723509 has 2 divisors, whose sum is σ = 213723510. Its totient is φ = 213723508.

The previous prime is 213723491. The next prime is 213723557. The reversal of 213723509 is 905327312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 202265284 + 11458225 = 14222^2 + 3385^2 .

It is a cyclic number.

It is not a de Polignac number, because 213723509 - 2⁸ = 213723253 is a prime.

It is a Chen prime.

It is equal to p_11795621 and since 213723509 and 11795621 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213723569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106861754 + 106861755.

It is an arithmetic number, because the mean of its divisors is an integer number (106861755).

Almost surely, 2^213723509 is an apocalyptic number.

It is an amenable number.

213723509 is a deficient number, since it is larger than the sum of its proper divisors (1).

213723509 is an equidigital number, since it uses as much as digits as its factorization.

213723509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11340, while the sum is 32.

The square root of 213723509 is about 14619.2855160572. The cubic root of 213723509 is about 597.8846891603.

The spelling of 213723509 in words is "two hundred thirteen million, seven hundred twenty-three thousand, five hundred nine".