21123029 has 2 divisors, whose sum is σ = 21123030. Its totient is φ = 21123028.

The previous prime is 21123017. The next prime is 21123043. The reversal of 21123029 is 92032112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18879025 + 2244004 = 4345^2 + 1498^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123029 - 2⁴ = 21123013 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21123029.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21125029) 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, 10561514 + 10561515.

It is an arithmetic number, because the mean of its divisors is an integer number (10561515).

Almost surely, 2^21123029 is an apocalyptic number.

It is an amenable number.

21123029 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123029 is an equidigital number, since it uses as much as digits as its factorization.

21123029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21123029 is about 4595.9796561778. The cubic root of 21123029 is about 276.4301430081.

The spelling of 21123029 in words is "twenty-one million, one hundred twenty-three thousand, twenty-nine".