23531765921 has 4 divisors (see below), whose sum is σ = 23532117012. Its totient is φ = 23531414832.

The previous prime is 23531765897. The next prime is 23531765947. The reversal of 23531765921 is 12956713532.

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 18467451025 + 5064314896 = 135895^2 + 71164^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23531765921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23531765021) 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, 40250 + ... + 220643.

It is an arithmetic number, because the mean of its divisors is an integer number (5883029253).

Almost surely, 2^23531765921 is an apocalyptic number.

It is an amenable number.

23531765921 is a deficient number, since it is larger than the sum of its proper divisors (351091).

23531765921 is an equidigital number, since it uses as much as digits as its factorization.

23531765921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351090.

The product of its digits is 340200, while the sum is 44.

The spelling of 23531765921 in words is "twenty-three billion, five hundred thirty-one million, seven hundred sixty-five thousand, nine hundred twenty-one".