129223021 has 4 divisors (see below), whose sum is σ = 132374844. Its totient is φ = 126071200.

The previous prime is 129223019. The next prime is 129223037. The reversal of 129223021 is 120322921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120322921 = 953 ⋅126257.

It can be written as a sum of positive squares in 2 ways, for example, as 76370121 + 52852900 = 8739^2 + 7270^2 .

It is a cyclic number.

It is not a de Polignac number, because 129223021 - 2¹ = 129223019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 129222983 and 129223001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129223091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1575850 + ... + 1575931.

It is an arithmetic number, because the mean of its divisors is an integer number (33093711).

Almost surely, 2^129223021 is an apocalyptic number.

It is an amenable number.

129223021 is a deficient number, since it is larger than the sum of its proper divisors (3151823).

129223021 is an equidigital number, since it uses as much as digits as its factorization.

129223021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3151822.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 129223021 is about 11367.6304039144. The cubic root of 129223021 is about 505.5684491946.

Adding to 129223021 its reverse (120322921), we get a palindrome (249545942).

The spelling of 129223021 in words is "one hundred twenty-nine million, two hundred twenty-three thousand, twenty-one".