21045137 has 2 divisors, whose sum is σ = 21045138. Its totient is φ = 21045136.

The previous prime is 21045127. The next prime is 21045139. The reversal of 21045137 is 73154012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16032016 + 5013121 = 4004^2 + 2239^2 .

It is a cyclic number.

It is not a de Polignac number, because 21045137 - 2²² = 16850833 is a prime.

Together with 21045139, 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 (21045139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522568 + 10522569.

It is an arithmetic number, because the mean of its divisors is an integer number (10522569).

Almost surely, 2^21045137 is an apocalyptic number.

It is an amenable number.

21045137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21045137 is an equidigital number, since it uses as much as digits as its factorization.

21045137 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21045137 is about 4587.4979019069. The cubic root of 21045137 is about 276.0899421563.

Adding to 21045137 its reverse (73154012), we get a palindrome (94199149).

The spelling of 21045137 in words is "twenty-one million, forty-five thousand, one hundred thirty-seven".