21055478867 has 4 divisors (see below), whose sum is σ = 21063406056. Its totient is φ = 21047551680.

The previous prime is 21055478849. The next prime is 21055478887. The reversal of 21055478867 is 76887455012.

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 21055478867 - 2³² = 16760511571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055478887) 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, 3959609 + ... + 3964922.

It is an arithmetic number, because the mean of its divisors is an integer number (5265851514).

Almost surely, 2^21055478867 is an apocalyptic number.

21055478867 is a deficient number, since it is larger than the sum of its proper divisors (7927189).

21055478867 is an equidigital number, since it uses as much as digits as its factorization.

21055478867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7927188.

The product of its (nonzero) digits is 3763200, while the sum is 53.

The spelling of 21055478867 in words is "twenty-one billion, fifty-five million, four hundred seventy-eight thousand, eight hundred sixty-seven".