21121671211 has 4 divisors (see below), whose sum is σ = 21128712424. Its totient is φ = 21114630000.

The previous prime is 21121671209. The next prime is 21121671227. The reversal of 21121671211 is 11217612112.

It is a happy number.

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 21121671211 - 2¹ = 21121671209 is a prime.

It is a super-2 number, since 2×21121671211² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121671911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3516105 + ... + 3522106.

It is an arithmetic number, because the mean of its divisors is an integer number (5282178106).

Almost surely, 2^21121671211 is an apocalyptic number.

21121671211 is a deficient number, since it is larger than the sum of its proper divisors (7041213).

21121671211 is an equidigital number, since it uses as much as digits as its factorization.

21121671211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7041212.

The product of its digits is 336, while the sum is 25.

The spelling of 21121671211 in words is "twenty-one billion, one hundred twenty-one million, six hundred seventy-one thousand, two hundred eleven".