16642121 has 2 divisors, whose sum is σ = 16642122. Its totient is φ = 16642120.

The previous prime is 16642111. The next prime is 16642123. The reversal of 16642121 is 12124661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16516096 + 126025 = 4064^2 + 355^2 .

It is an emirp because it is prime and its reverse (12124661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16642121 - 2¹⁴ = 16625737 is a prime.

Together with 16642123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16642123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8321060 + 8321061.

It is an arithmetic number, because the mean of its divisors is an integer number (8321061).

Almost surely, 2^16642121 is an apocalyptic number.

It is an amenable number.

16642121 is a deficient number, since it is larger than the sum of its proper divisors (1).

16642121 is an equidigital number, since it uses as much as digits as its factorization.

16642121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 23.

The square root of 16642121 is about 4079.4755790420. The cubic root of 16642121 is about 255.3110186824.

Adding to 16642121 its reverse (12124661), we get a palindrome (28766782).

The spelling of 16642121 in words is "sixteen million, six hundred forty-two thousand, one hundred twenty-one".