213662561 has 4 divisors (see below), whose sum is σ = 244185792. Its totient is φ = 183139332.

The previous prime is 213662549. The next prime is 213662591. The reversal of 213662561 is 165266312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 213662561 - 2⁶ = 213662497 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (213662591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15261605 + ... + 15261618.

It is an arithmetic number, because the mean of its divisors is an integer number (61046448).

Almost surely, 2^213662561 is an apocalyptic number.

It is an amenable number.

213662561 is a deficient number, since it is larger than the sum of its proper divisors (30523231).

213662561 is an equidigital number, since it uses as much as digits as its factorization.

213662561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30523230.

The product of its digits is 12960, while the sum is 32.

The square root of 213662561 is about 14617.2008606299. The cubic root of 213662561 is about 597.8278503960.

The spelling of 213662561 in words is "two hundred thirteen million, six hundred sixty-two thousand, five hundred sixty-one".