21427433 has 4 divisors (see below), whose sum is σ = 22166340. Its totient is φ = 20688528.

The previous prime is 21427381. The next prime is 21427447. The reversal of 21427433 is 33472412.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6620329 + 14807104 = 2573^2 + 3848^2 .

It is a cyclic number.

It is not a de Polignac number, because 21427433 - 2⁶ = 21427369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427333) 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, 369410 + ... + 369467.

It is an arithmetic number, because the mean of its divisors is an integer number (5541585).

Almost surely, 2^21427433 is an apocalyptic number.

It is an amenable number.

21427433 is a deficient number, since it is larger than the sum of its proper divisors (738907).

21427433 is an equidigital number, since it uses as much as digits as its factorization.

21427433 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738906.

The product of its digits is 4032, while the sum is 26.

The square root of 21427433 is about 4628.9775328900. The cubic root of 21427433 is about 277.7516932958.

Adding to 21427433 its reverse (33472412), we get a palindrome (54899845).

The spelling of 21427433 in words is "twenty-one million, four hundred twenty-seven thousand, four hundred thirty-three".