21240434356 has 6 divisors (see below), whose sum is σ = 37170760130. Its totient is φ = 10620217176.

The previous prime is 21240434339. The next prime is 21240434357. The reversal of 21240434356 is 65343404212.

It can be written as a sum of positive squares in only one way, i.e., 14035140900 + 7205293456 = 118470^2 + 84884^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240434357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2655054291 + ... + 2655054298.

Almost surely, 2^21240434356 is an apocalyptic number.

It is an amenable number.

21240434356 is a deficient number, since it is larger than the sum of its proper divisors (15930325774).

21240434356 is a wasteful number, since it uses less digits than its factorization.

21240434356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5310108593 (or 5310108591 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 34.

Adding to 21240434356 its reverse (65343404212), we get a palindrome (86583838568).

The spelling of 21240434356 in words is "twenty-one billion, two hundred forty million, four hundred thirty-four thousand, three hundred fifty-six".