16212561 has 4 divisors (see below), whose sum is σ = 21616752. Its totient is φ = 10808372.

The previous prime is 16212557. The next prime is 16212571. The reversal of 16212561 is 16521261.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16521261 = 3 ⋅5507087.

It is a cyclic number.

It is not a de Polignac number, because 16212561 - 2² = 16212557 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16212571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2702091 + ... + 2702096.

It is an arithmetic number, because the mean of its divisors is an integer number (5404188).

Almost surely, 2^16212561 is an apocalyptic number.

It is an amenable number.

16212561 is a deficient number, since it is larger than the sum of its proper divisors (5404191).

16212561 is an equidigital number, since it uses as much as digits as its factorization.

16212561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5404190.

The product of its digits is 720, while the sum is 24.

The square root of 16212561 is about 4026.4824599146. The cubic root of 16212561 is about 253.0951799652.

The spelling of 16212561 in words is "sixteen million, two hundred twelve thousand, five hundred sixty-one".