21115515550266 has 24 divisors (see below), whose sum is σ = 45756301387680. Its totient is φ = 7037579384136.

The previous prime is 21115515550253. The next prime is 21115515550273. The reversal of 21115515550266 is 66205551551112.

21115515550266 is a `hidden beast` number, since 2 + 1 + 11 + 55 + 15 + 550 + 26 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 77009286 + ... + 77282993.

It is an arithmetic number, because the mean of its divisors is an integer number (1906512557820).

Almost surely, 2^{21115515550266} is an apocalyptic number.

21115515550266 is an abundant number, since it is smaller than the sum of its proper divisors (24640785837414).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21115515550266 is a wasteful number, since it uses less digits than its factorization.

21115515550266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154299890 (or 154299887 counting only the distinct ones).

The product of its (nonzero) digits is 450000, while the sum is 45.

The spelling of 21115515550266 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred fifty thousand, two hundred sixty-six".