21115515550643 has 4 divisors (see below), whose sum is σ = 21210203961408. Its totient is φ = 21020827139880.

The previous prime is 21115515550601. The next prime is 21115515550667. The reversal of 21115515550643 is 34605551551112.

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 21115515550643 - 2⁸ = 21115515550387 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21115515550594 and 21115515550603.

It is not an unprimeable number, because it can be changed into a prime (21115115550643) 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, 47344205048 + ... + 47344205493.

It is an arithmetic number, because the mean of its divisors is an integer number (5302550990352).

Almost surely, 2^{21115515550643} is an apocalyptic number.

21115515550643 is a deficient number, since it is larger than the sum of its proper divisors (94688410765).

21115515550643 is an equidigital number, since it uses as much as digits as its factorization.

21115515550643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94688410764.

The product of its (nonzero) digits is 450000, while the sum is 44.

The spelling of 21115515550643 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred fifty thousand, six hundred forty-three".