21203424434 has 4 divisors (see below), whose sum is σ = 31805136654. Its totient is φ = 10601712216.

The previous prime is 21203424427. The next prime is 21203424439. The reversal of 21203424434 is 43442430212.

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

It can be written as a sum of positive squares in only one way, i.e., 17322508225 + 3880916209 = 131615^2 + 62297^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21203424397 and 21203424406.

It is not an unprimeable number, because it can be changed into a prime (21203424439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5300856107 + ... + 5300856110.

Almost surely, 2^21203424434 is an apocalyptic number.

21203424434 is a deficient number, since it is larger than the sum of its proper divisors (10601712220).

21203424434 is a wasteful number, since it uses less digits than its factorization.

21203424434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10601712219.

The product of its (nonzero) digits is 18432, while the sum is 29.

Adding to 21203424434 its reverse (43442430212), we get a palindrome (64645854646).

The spelling of 21203424434 in words is "twenty-one billion, two hundred three million, four hundred twenty-four thousand, four hundred thirty-four".