21229427 has 4 divisors (see below), whose sum is σ = 21241920. Its totient is φ = 21216936.

The previous prime is 21229409. The next prime is 21229463. The reversal of 21229427 is 72492212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21229427 - 2²⁰ = 20180851 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 21229427.

It is not an unprimeable number, because it can be changed into a prime (21229727) 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, 3203 + ... + 7260.

It is an arithmetic number, because the mean of its divisors is an integer number (5310480).

Almost surely, 2^21229427 is an apocalyptic number.

21229427 is a deficient number, since it is larger than the sum of its proper divisors (12493).

21229427 is a wasteful number, since it uses less digits than its factorization.

21229427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12492.

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

The square root of 21229427 is about 4607.5402331396. The cubic root of 21229427 is about 276.8934977883.

The spelling of 21229427 in words is "twenty-one million, two hundred twenty-nine thousand, four hundred twenty-seven".