21216053 has 2 divisors, whose sum is σ = 21216054. Its totient is φ = 21216052.

The previous prime is 21216047. The next prime is 21216061. The reversal of 21216053 is 35061212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11437924 + 9778129 = 3382^2 + 3127^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21216053 is a prime.

It is equal to p_1342730 and since 21216053 and 1342730 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 (21216073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608026 + 10608027.

It is an arithmetic number, because the mean of its divisors is an integer number (10608027).

Almost surely, 2^21216053 is an apocalyptic number.

It is an amenable number.

21216053 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216053 is an equidigital number, since it uses as much as digits as its factorization.

21216053 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21216053 is about 4606.0886878131. The cubic root of 21216053 is about 276.8353402829.

Adding to 21216053 its reverse (35061212), we get a palindrome (56277265).

The spelling of 21216053 in words is "twenty-one million, two hundred sixteen thousand, fifty-three".