21207552771 has 4 divisors (see below), whose sum is σ = 28276737032. Its totient is φ = 14138368512.

The previous prime is 21207552763. The next prime is 21207552787. The reversal of 21207552771 is 17725570212.

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

It is not a de Polignac number, because 21207552771 - 2³ = 21207552763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21207552271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3534592126 + ... + 3534592131.

It is an arithmetic number, because the mean of its divisors is an integer number (7069184258).

Almost surely, 2^21207552771 is an apocalyptic number.

21207552771 is a deficient number, since it is larger than the sum of its proper divisors (7069184261).

21207552771 is an equidigital number, since it uses as much as digits as its factorization.

21207552771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7069184260.

The product of its (nonzero) digits is 68600, while the sum is 39.

The spelling of 21207552771 in words is "twenty-one billion, two hundred seven million, five hundred fifty-two thousand, seven hundred seventy-one".