21023129 has 4 divisors (see below), whose sum is σ = 21149184. Its totient is φ = 20897076.

The previous prime is 21023117. The next prime is 21023137. The reversal of 21023129 is 92132012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21023129 - 2⁴ = 21023113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21023129.

It is not an unprimeable number, because it can be changed into a prime (21025129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62777 + ... + 63110.

It is an arithmetic number, because the mean of its divisors is an integer number (5287296).

Almost surely, 2^21023129 is an apocalyptic number.

It is an amenable number.

21023129 is a deficient number, since it is larger than the sum of its proper divisors (126055).

21023129 is a wasteful number, since it uses less digits than its factorization.

21023129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126054.

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

The square root of 21023129 is about 4585.0985812739. The cubic root of 21023129 is about 275.9936680267.

The spelling of 21023129 in words is "twenty-one million, twenty-three thousand, one hundred twenty-nine".