21265066217771 has 4 divisors (see below), whose sum is σ = 21265151914152. Its totient is φ = 21264980521392.

The previous prime is 21265066217749. The next prime is 21265066217803. The reversal of 21265066217771 is 17771266056212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21265066217771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21265066211771) 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, 42474890 + ... + 42972623.

It is an arithmetic number, because the mean of its divisors is an integer number (5316287978538).

Almost surely, 2^{21265066217771} is an apocalyptic number.

21265066217771 is a deficient number, since it is larger than the sum of its proper divisors (85696381).

21265066217771 is an equidigital number, since it uses as much as digits as its factorization.

21265066217771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85696380.

The product of its (nonzero) digits is 2963520, while the sum is 53.

The spelling of 21265066217771 in words is "twenty-one trillion, two hundred sixty-five billion, sixty-six million, two hundred seventeen thousand, seven hundred seventy-one".