21245023543 has 4 divisors (see below), whose sum is σ = 21260634768. Its totient is φ = 21229412320.

The previous prime is 21245023531. The next prime is 21245023549. The reversal of 21245023543 is 34532054212.

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 21245023543 - 2³³ = 12655088951 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 (21245023549) 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 3 ways as a sum of consecutive naturals, for example, 7803571 + ... + 7806292.

It is an arithmetic number, because the mean of its divisors is an integer number (5315158692).

Almost surely, 2^21245023543 is an apocalyptic number.

21245023543 is a deficient number, since it is larger than the sum of its proper divisors (15611225).

21245023543 is a wasteful number, since it uses less digits than its factorization.

21245023543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15611224.

The product of its (nonzero) digits is 28800, while the sum is 31.

Adding to 21245023543 its reverse (34532054212), we get a palindrome (55777077755).

The spelling of 21245023543 in words is "twenty-one billion, two hundred forty-five million, twenty-three thousand, five hundred forty-three".