21427229 has 4 divisors (see below), whose sum is σ = 21439584. Its totient is φ = 21414876.

The previous prime is 21427223. The next prime is 21427247. The reversal of 21427229 is 92272412.

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 21427229 - 2⁴ = 21427213 is a prime.

It is a super-2 number, since 2×21427229² = 918252285236882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3047 + ... + 7220.

It is an arithmetic number, because the mean of its divisors is an integer number (5359896).

Almost surely, 2^21427229 is an apocalyptic number.

It is an amenable number.

21427229 is a deficient number, since it is larger than the sum of its proper divisors (12355).

21427229 is a wasteful number, since it uses less digits than its factorization.

21427229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12354.

The product of its digits is 4032, while the sum is 29.

The square root of 21427229 is about 4628.9554977338. The cubic root of 21427229 is about 277.7508118475.

The spelling of 21427229 in words is "twenty-one million, four hundred twenty-seven thousand, two hundred twenty-nine".