21071211667 has 16 divisors (see below), whose sum is σ = 23104972800. Its totient is φ = 19057278240.

The previous prime is 21071211653. The next prime is 21071211677. The reversal of 21071211667 is 76611217012.

It is a de Polignac number, because none of the positive numbers 2^k-21071211667 is a prime.

It is a super-2 number, since 2×21071211667² (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 (21071211607) 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 15 ways as a sum of consecutive naturals, for example, 5064334 + ... + 5068492.

It is an arithmetic number, because the mean of its divisors is an integer number (1444060800).

Almost surely, 2^21071211667 is an apocalyptic number.

21071211667 is a deficient number, since it is larger than the sum of its proper divisors (2033761133).

21071211667 is a wasteful number, since it uses less digits than its factorization.

21071211667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6426.

The product of its (nonzero) digits is 7056, while the sum is 34.

Adding to 21071211667 its reverse (76611217012), we get a palindrome (97682428679).

The spelling of 21071211667 in words is "twenty-one billion, seventy-one million, two hundred eleven thousand, six hundred sixty-seven".