21201323523 has 4 divisors (see below), whose sum is σ = 28268431368. Its totient is φ = 14134215680.

The previous prime is 21201323467. The next prime is 21201323537. The reversal of 21201323523 is 32532310212.

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 21201323523 - 2¹⁷ = 21201192451 is a prime.

It is a super-4 number, since 4×21201323523⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21201323493 and 21201323502.

It is not an unprimeable number, because it can be changed into a prime (21201323023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3533553918 + ... + 3533553923.

It is an arithmetic number, because the mean of its divisors is an integer number (7067107842).

Almost surely, 2^21201323523 is an apocalyptic number.

21201323523 is a deficient number, since it is larger than the sum of its proper divisors (7067107845).

21201323523 is an equidigital number, since it uses as much as digits as its factorization.

21201323523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7067107844.

The product of its (nonzero) digits is 2160, while the sum is 24.

Adding to 21201323523 its reverse (32532310212), we get a palindrome (53733633735).

The spelling of 21201323523 in words is "twenty-one billion, two hundred one million, three hundred twenty-three thousand, five hundred twenty-three".