21273073 has 2 divisors, whose sum is σ = 21273074. Its totient is φ = 21273072.

The previous prime is 21273071. The next prime is 21273097. The reversal of 21273073 is 37037212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16875664 + 4397409 = 4108^2 + 2097^2 .

It is a cyclic number.

It is not a de Polignac number, because 21273073 - 2¹ = 21273071 is a prime.

Together with 21273071, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21273071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10636536 + 10636537.

It is an arithmetic number, because the mean of its divisors is an integer number (10636537).

Almost surely, 2^21273073 is an apocalyptic number.

It is an amenable number.

21273073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21273073 is an equidigital number, since it uses as much as digits as its factorization.

21273073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 25.

The square root of 21273073 is about 4612.2741679133. The cubic root of 21273073 is about 277.0831248395.

The spelling of 21273073 in words is "twenty-one million, two hundred seventy-three thousand, seventy-three".