21520636243 has 8 divisors (see below), whose sum is σ = 23074994880. Its totient is φ = 19998326400.

The previous prime is 21520636237. The next prime is 21520636253. The reversal of 21520636243 is 34263602512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21520636243 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21520636199 and 21520636208.

It is not an unprimeable number, because it can be changed into a prime (21520636223) 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 7 ways as a sum of consecutive naturals, for example, 8010808 + ... + 8013493.

It is an arithmetic number, because the mean of its divisors is an integer number (2884374360).

Almost surely, 2^21520636243 is an apocalyptic number.

21520636243 is a deficient number, since it is larger than the sum of its proper divisors (1554358637).

21520636243 is a wasteful number, since it uses less digits than its factorization.

21520636243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16024397.

The product of its (nonzero) digits is 51840, while the sum is 34.

The spelling of 21520636243 in words is "twenty-one billion, five hundred twenty million, six hundred thirty-six thousand, two hundred forty-three".