21280029 has 4 divisors (see below), whose sum is σ = 28373376. Its totient is φ = 14186684.

The previous prime is 21280013. The next prime is 21280067. The reversal of 21280029 is 92008212.

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 21280029 - 2⁴ = 21280013 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21279990 and 21280008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280079) 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, 3546669 + ... + 3546674.

It is an arithmetic number, because the mean of its divisors is an integer number (7093344).

Almost surely, 2^21280029 is an apocalyptic number.

It is an amenable number.

21280029 is a deficient number, since it is larger than the sum of its proper divisors (7093347).

21280029 is an equidigital number, since it uses as much as digits as its factorization.

21280029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7093346.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21280029 is about 4613.0281811409. The cubic root of 21280029 is about 277.1133223287.

The spelling of 21280029 in words is "twenty-one million, two hundred eighty thousand, twenty-nine".