21253243423 has 4 divisors (see below), whose sum is σ = 21254402440. Its totient is φ = 21252084408.

The previous prime is 21253243409. The next prime is 21253243439. The reversal of 21253243423 is 32434235212.

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

It is a cyclic number.

It is not a de Polignac number, because 21253243423 - 2¹⁷ = 21253112351 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253243493) 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, 551553 + ... + 588826.

It is an arithmetic number, because the mean of its divisors is an integer number (5313600610).

Almost surely, 2^21253243423 is an apocalyptic number.

21253243423 is a deficient number, since it is larger than the sum of its proper divisors (1159017).

21253243423 is a wasteful number, since it uses less digits than its factorization.

21253243423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1159016.

The product of its digits is 34560, while the sum is 31.

Adding to 21253243423 its reverse (32434235212), we get a palindrome (53687478635).

The spelling of 21253243423 in words is "twenty-one billion, two hundred fifty-three million, two hundred forty-three thousand, four hundred twenty-three".