21206711999 has 16 divisors (see below), whose sum is σ = 25340130720. Its totient is φ = 17519093760.

The previous prime is 21206711993. The next prime is 21206712001. The reversal of 21206711999 is 99911760212.

It is a cyclic number.

It is not a de Polignac number, because 21206711999 - 2¹² = 21206707903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206711993) 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, 1949834 + ... + 1960679.

It is an arithmetic number, because the mean of its divisors is an integer number (1583758170).

Almost surely, 2^21206711999 is an apocalyptic number.

21206711999 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21206711999 is a deficient number, since it is larger than the sum of its proper divisors (4133418721).

21206711999 is a wasteful number, since it uses less digits than its factorization.

21206711999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3910570.

The product of its (nonzero) digits is 122472, while the sum is 47.

The spelling of 21206711999 in words is "twenty-one billion, two hundred six million, seven hundred eleven thousand, nine hundred ninety-nine".