21745547423 has 4 divisors (see below), whose sum is σ = 21750890448. Its totient is φ = 21740204400.

The previous prime is 21745547407. The next prime is 21745547429. The reversal of 21745547423 is 32474554712.

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 21745547423 - 2⁴ = 21745547407 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 (21745547429) 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, 2665403 + ... + 2673548.

It is an arithmetic number, because the mean of its divisors is an integer number (5437722612).

Almost surely, 2^21745547423 is an apocalyptic number.

21745547423 is a deficient number, since it is larger than the sum of its proper divisors (5343025).

21745547423 is an equidigital number, since it uses as much as digits as its factorization.

21745547423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5343024.

The product of its digits is 940800, while the sum is 44.

The spelling of 21745547423 in words is "twenty-one billion, seven hundred forty-five million, five hundred forty-seven thousand, four hundred twenty-three".