21235425447 has 16 divisors (see below), whose sum is σ = 28955793888. Its totient is φ = 13839436800.

The previous prime is 21235425443. The next prime is 21235425457. The reversal of 21235425447 is 74452453212.

It is not a de Polignac number, because 21235425447 - 2² = 21235425443 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21235425443) 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 in 15 ways as a sum of consecutive naturals, for example, 404304 + ... + 453797.

It is an arithmetic number, because the mean of its divisors is an integer number (1809737118).

Almost surely, 2^21235425447 is an apocalyptic number.

21235425447 is a deficient number, since it is larger than the sum of its proper divisors (7720368441).

21235425447 is a wasteful number, since it uses less digits than its factorization.

21235425447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 858290.

The product of its digits is 268800, while the sum is 39.

Adding to 21235425447 its reverse (74452453212), we get a palindrome (95687878659).

The spelling of 21235425447 in words is "twenty-one billion, two hundred thirty-five million, four hundred twenty-five thousand, four hundred forty-seven".