21445973723 has 4 divisors (see below), whose sum is σ = 21460056648. Its totient is φ = 21431890800.

The previous prime is 21445973699. The next prime is 21445973749. The reversal of 21445973723 is 32737954412.

It is a happy number.

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 21445973723 - 2²⁰ = 21444925147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21445973753) 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, 7039178 + ... + 7042223.

It is an arithmetic number, because the mean of its divisors is an integer number (5365014162).

Almost surely, 2^21445973723 is an apocalyptic number.

21445973723 is a deficient number, since it is larger than the sum of its proper divisors (14082925).

21445973723 is a wasteful number, since it uses less digits than its factorization.

21445973723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14082924.

The product of its digits is 1270080, while the sum is 47.

The spelling of 21445973723 in words is "twenty-one billion, four hundred forty-five million, nine hundred seventy-three thousand, seven hundred twenty-three".