21028129 has 8 divisors (see below), whose sum is σ = 21541248. Its totient is φ = 20517840.

The previous prime is 21028127. The next prime is 21028153. The reversal of 21028129 is 92182012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21028129 - 2¹ = 21028127 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21028123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25014 + ... + 25840.

It is an arithmetic number, because the mean of its divisors is an integer number (2692656).

Almost surely, 2^21028129 is an apocalyptic number.

It is an amenable number.

21028129 is a deficient number, since it is larger than the sum of its proper divisors (513119).

21028129 is an equidigital number, since it uses as much as digits as its factorization.

21028129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1415.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21028129 is about 4585.6437934057. The cubic root of 21028129 is about 276.0155464533.

The spelling of 21028129 in words is "twenty-one million, twenty-eight thousand, one hundred twenty-nine".