23645389721 has 4 divisors (see below), whose sum is σ = 23649416244. Its totient is φ = 23641363200.

The previous prime is 23645389693. The next prime is 23645389727. The reversal of 23645389721 is 12798354632.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16828575625 + 6816814096 = 129725^2 + 82564^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23645389721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 23645389721.

It is not an unprimeable number, because it can be changed into a prime (23645389727) 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, 2004440 + ... + 2016201.

It is an arithmetic number, because the mean of its divisors is an integer number (5912354061).

Almost surely, 2^23645389721 is an apocalyptic number.

It is an amenable number.

23645389721 is a deficient number, since it is larger than the sum of its proper divisors (4026523).

23645389721 is an equidigital number, since it uses as much as digits as its factorization.

23645389721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4026522.

The product of its digits is 2177280, while the sum is 50.

The spelling of 23645389721 in words is "twenty-three billion, six hundred forty-five million, three hundred eighty-nine thousand, seven hundred twenty-one".