129215421 has 12 divisors (see below), whose sum is σ = 186748380. Its totient is φ = 86095680.

The previous prime is 129215417. The next prime is 129215423. The reversal of 129215421 is 124512921.

129215421 is a `hidden beast` number, since 1 + 29 + 215 + 421 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 113103225 + 16112196 = 10635^2 + 4014^2 .

It is not a de Polignac number, because 129215421 - 2² = 129215417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129215423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21931 + ... + 27191.

It is an arithmetic number, because the mean of its divisors is an integer number (15562365).

Almost surely, 2^129215421 is an apocalyptic number.

It is an amenable number.

129215421 is a deficient number, since it is larger than the sum of its proper divisors (57532959).

129215421 is a wasteful number, since it uses less digits than its factorization.

129215421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7996 (or 7993 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 129215421 is about 11367.2961164914. The cubic root of 129215421 is about 505.5585376595.

The spelling of 129215421 in words is "one hundred twenty-nine million, two hundred fifteen thousand, four hundred twenty-one".