21267437 has 2 divisors, whose sum is σ = 21267438. Its totient is φ = 21267436.

The previous prime is 21267401. The next prime is 21267439. The reversal of 21267437 is 73476212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18541636 + 2725801 = 4306^2 + 1651^2 .

It is a cyclic number.

It is not a de Polignac number, because 21267437 - 2¹⁴ = 21251053 is a prime.

Together with 21267439, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21267439) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10633718 + 10633719.

It is an arithmetic number, because the mean of its divisors is an integer number (10633719).

Almost surely, 2^21267437 is an apocalyptic number.

It is an amenable number.

21267437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21267437 is an equidigital number, since it uses as much as digits as its factorization.

21267437 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 32.

The square root of 21267437 is about 4611.6631490168. The cubic root of 21267437 is about 277.0586529258.

The spelling of 21267437 in words is "twenty-one million, two hundred sixty-seven thousand, four hundred thirty-seven".