16243921 has 2 divisors, whose sum is σ = 16243922. Its totient is φ = 16243920.

The previous prime is 16243919. The next prime is 16243933. The reversal of 16243921 is 12934261.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16160400 + 83521 = 4020^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 16243921 - 2¹ = 16243919 is a prime.

Together with 16243919, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 16243921.

It is not a weakly prime, because it can be changed into another prime (16243961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8121960 + 8121961.

It is an arithmetic number, because the mean of its divisors is an integer number (8121961).

Almost surely, 2^16243921 is an apocalyptic number.

It is an amenable number.

16243921 is a deficient number, since it is larger than the sum of its proper divisors (1).

16243921 is an equidigital number, since it uses as much as digits as its factorization.

16243921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 28.

The square root of 16243921 is about 4030.3747964674. The cubic root of 16243921 is about 253.2582624208.

The spelling of 16243921 in words is "sixteen million, two hundred forty-three thousand, nine hundred twenty-one".