21061223 has 2 divisors, whose sum is σ = 21061224. Its totient is φ = 21061222.

The previous prime is 21061207. The next prime is 21061237. The reversal of 21061223 is 32216012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21061223 - 2⁴ = 21061207 is a prime.

It is a super-2 number, since 2×21061223² = 887150228511458, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21063223) 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, 10530611 + 10530612.

It is an arithmetic number, because the mean of its divisors is an integer number (10530612).

Almost surely, 2^21061223 is an apocalyptic number.

21061223 is a deficient number, since it is larger than the sum of its proper divisors (1).

21061223 is an equidigital number, since it uses as much as digits as its factorization.

21061223 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21061223 is about 4589.2508103175. The cubic root of 21061223 is about 276.1602680110.

Adding to 21061223 its reverse (32216012), we get a palindrome (53277235).

The spelling of 21061223 in words is "twenty-one million, sixty-one thousand, two hundred twenty-three".