23661618721 has 4 divisors (see below), whose sum is σ = 25481743252. Its totient is φ = 21841494192.

The previous prime is 23661618653. The next prime is 23661618727. The reversal of 23661618721 is 12781616632.

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 4255735696 + 19405883025 = 65236^2 + 139305^2 .

It is a cyclic number.

It is not a de Polignac number, because 23661618721 - 2¹⁷ = 23661487649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23661618727) 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, 910062246 + ... + 910062271.

It is an arithmetic number, because the mean of its divisors is an integer number (6370435813).

Almost surely, 2^23661618721 is an apocalyptic number.

It is an amenable number.

23661618721 is a deficient number, since it is larger than the sum of its proper divisors (1820124531).

23661618721 is a wasteful number, since it uses less digits than its factorization.

23661618721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1820124530.

The product of its digits is 145152, while the sum is 43.

The spelling of 23661618721 in words is "twenty-three billion, six hundred sixty-one million, six hundred eighteen thousand, seven hundred twenty-one".