21155555263 has 4 divisors (see below), whose sum is σ = 22269005560. Its totient is φ = 20042104968.

The previous prime is 21155555261. The next prime is 21155555287. The reversal of 21155555263 is 36255555112.

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 21155555263 - 2¹ = 21155555261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155555261) 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, 556725120 + ... + 556725157.

It is an arithmetic number, because the mean of its divisors is an integer number (5567251390).

Almost surely, 2^21155555263 is an apocalyptic number.

21155555263 is a deficient number, since it is larger than the sum of its proper divisors (1113450297).

21155555263 is a wasteful number, since it uses less digits than its factorization.

21155555263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1113450296.

The product of its digits is 225000, while the sum is 40.

The spelling of 21155555263 in words is "twenty-one billion, one hundred fifty-five million, five hundred fifty-five thousand, two hundred sixty-three".