21231173 has 2 divisors, whose sum is σ = 21231174. Its totient is φ = 21231172.

The previous prime is 21231143. The next prime is 21231241. The reversal of 21231173 is 37113212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21224449 + 6724 = 4607^2 + 82^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231173 - 2¹⁸ = 20969029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21231143) 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, 10615586 + 10615587.

It is an arithmetic number, because the mean of its divisors is an integer number (10615587).

Almost surely, 2^21231173 is an apocalyptic number.

It is an amenable number.

21231173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231173 is an equidigital number, since it uses as much as digits as its factorization.

21231173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 252, while the sum is 20.

The square root of 21231173 is about 4607.7297012737. The cubic root of 21231173 is about 276.9010885537.

Adding to 21231173 its reverse (37113212), we get a palindrome (58344385).

The spelling of 21231173 in words is "twenty-one million, two hundred thirty-one thousand, one hundred seventy-three".