21267621545761 has 4 divisors (see below), whose sum is σ = 21271469501632. Its totient is φ = 21263773589892.

The previous prime is 21267621545719. The next prime is 21267621545873. The reversal of 21267621545761 is 16754512676212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21267621545761 - 2⁷ = 21267621545633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21267621545701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1923969645 + ... + 1923980698.

It is an arithmetic number, because the mean of its divisors is an integer number (5317867375408).

Almost surely, 2^{21267621545761} is an apocalyptic number.

It is an amenable number.

21267621545761 is a deficient number, since it is larger than the sum of its proper divisors (3847955871).

21267621545761 is an equidigital number, since it uses as much as digits as its factorization.

21267621545761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3847955870.

The product of its digits is 8467200, while the sum is 55.

The spelling of 21267621545761 in words is "twenty-one trillion, two hundred sixty-seven billion, six hundred twenty-one million, five hundred forty-five thousand, seven hundred sixty-one".