21420229 has 4 divisors (see below), whose sum is σ = 21453984. Its totient is φ = 21386476.

The previous prime is 21420227. The next prime is 21420233. The reversal of 21420229 is 92202412.

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 21420229 - 2¹ = 21420227 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420227) 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, 15907 + ... + 17200.

It is an arithmetic number, because the mean of its divisors is an integer number (5363496).

Almost surely, 2^21420229 is an apocalyptic number.

It is an amenable number.

21420229 is a deficient number, since it is larger than the sum of its proper divisors (33755).

21420229 is an equidigital number, since it uses as much as digits as its factorization.

21420229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33754.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21420229 is about 4628.1993258718. The cubic root of 21420229 is about 277.7205626812.

The spelling of 21420229 in words is "twenty-one million, four hundred twenty thousand, two hundred twenty-nine".