21273437 has 2 divisors, whose sum is σ = 21273438. Its totient is φ = 21273436.

The previous prime is 21273431. The next prime is 21273449. The reversal of 21273437 is 73437212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16859236 + 4414201 = 4106^2 + 2101^2 .

It is a cyclic number.

It is not a de Polignac number, because 21273437 - 2⁸ = 21273181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21273431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10636718 + 10636719.

It is an arithmetic number, because the mean of its divisors is an integer number (10636719).

Almost surely, 2^21273437 is an apocalyptic number.

It is an amenable number.

21273437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21273437 is an equidigital number, since it uses as much as digits as its factorization.

21273437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 29.

The square root of 21273437 is about 4612.3136276710. The cubic root of 21273437 is about 277.0847052049.

The spelling of 21273437 in words is "twenty-one million, two hundred seventy-three thousand, four hundred thirty-seven".