21161237 has 2 divisors, whose sum is σ = 21161238. Its totient is φ = 21161236.

The previous prime is 21161227. The next prime is 21161279. The reversal of 21161237 is 73216112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14432401 + 6728836 = 3799^2 + 2594^2 .

It is a cyclic number.

It is not a de Polignac number, because 21161237 - 2¹⁸ = 20899093 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 (21161227) 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, 10580618 + 10580619.

It is an arithmetic number, because the mean of its divisors is an integer number (10580619).

Almost surely, 2^21161237 is an apocalyptic number.

It is an amenable number.

21161237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161237 is an equidigital number, since it uses as much as digits as its factorization.

21161237 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 23.

The square root of 21161237 is about 4600.1344545567. The cubic root of 21161237 is about 276.5967144643.

Adding to 21161237 its reverse (73216112), we get a palindrome (94377349).

The spelling of 21161237 in words is "twenty-one million, one hundred sixty-one thousand, two hundred thirty-seven".