23531510221 has 2 divisors, whose sum is σ = 23531510222. Its totient is φ = 23531510220.

The previous prime is 23531510209. The next prime is 23531510237. The reversal of 23531510221 is 12201513532.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22085229321 + 1446280900 = 148611^2 + 38030^2 .

It is a cyclic number.

It is not a de Polignac number, because 23531510221 - 2²⁹ = 22994639309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23531510201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11765755110 + 11765755111.

It is an arithmetic number, because the mean of its divisors is an integer number (11765755111).

Almost surely, 2^23531510221 is an apocalyptic number.

It is an amenable number.

23531510221 is a deficient number, since it is larger than the sum of its proper divisors (1).

23531510221 is an equidigital number, since it uses as much as digits as its factorization.

23531510221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 25.

The spelling of 23531510221 in words is "twenty-three billion, five hundred thirty-one million, five hundred ten thousand, two hundred twenty-one".