21213434 has 16 divisors (see below), whose sum is σ = 35060256. Its totient is φ = 9546000.

The previous prime is 21213431. The next prime is 21213449. The reversal of 21213434 is 43431212.

It is not an unprimeable number, because it can be changed into a prime (21213431) 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 7 ways as a sum of consecutive naturals, for example, 2552 + ... + 6995.

It is an arithmetic number, because the mean of its divisors is an integer number (2191266).

Almost surely, 2^21213434 is an apocalyptic number.

21213434 is a deficient number, since it is larger than the sum of its proper divisors (13846822).

21213434 is a wasteful number, since it uses less digits than its factorization.

21213434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9661.

The product of its digits is 576, while the sum is 20.

The square root of 21213434 is about 4605.8043814300. The cubic root of 21213434 is about 276.8239485694.

Adding to 21213434 its reverse (43431212), we get a palindrome (64644646).

It can be divided in two parts, 2121 and 3434, that added together give a palindrome (5555).

The spelling of 21213434 in words is "twenty-one million, two hundred thirteen thousand, four hundred thirty-four".