21263210642423 has 4 divisors (see below), whose sum is σ = 21461932237320. Its totient is φ = 21064489047528.

The previous prime is 21263210642417. The next prime is 21263210642441. The reversal of 21263210642423 is 32424601236212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21263210642423 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 (21263210641423) 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, 99360797288 + ... + 99360797501.

It is an arithmetic number, because the mean of its divisors is an integer number (5365483059330).

Almost surely, 2^{21263210642423} is an apocalyptic number.

21263210642423 is a deficient number, since it is larger than the sum of its proper divisors (198721594897).

21263210642423 is a wasteful number, since it uses less digits than its factorization.

21263210642423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198721594896.

The product of its (nonzero) digits is 165888, while the sum is 38.

Adding to 21263210642423 its reverse (32424601236212), we get a palindrome (53687811878635).

The spelling of 21263210642423 in words is "twenty-one trillion, two hundred sixty-three billion, two hundred ten million, six hundred forty-two thousand, four hundred twenty-three".