21016837 has 2 divisors, whose sum is σ = 21016838. Its totient is φ = 21016836.

The previous prime is 21016829. The next prime is 21016859. The reversal of 21016837 is 73861012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19793601 + 1223236 = 4449^2 + 1106^2 .

It is a cyclic number.

It is not a de Polignac number, because 21016837 - 2³ = 21016829 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21016817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10508418 + 10508419.

It is an arithmetic number, because the mean of its divisors is an integer number (10508419).

Almost surely, 2^21016837 is an apocalyptic number.

It is an amenable number.

21016837 is a deficient number, since it is larger than the sum of its proper divisors (1).

21016837 is an equidigital number, since it uses as much as digits as its factorization.

21016837 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21016837 is about 4584.4123941897. The cubic root of 21016837 is about 275.9661312848.

Adding to 21016837 its reverse (73861012), we get a palindrome (94877849).

The spelling of 21016837 in words is "twenty-one million, sixteen thousand, eight hundred thirty-seven".