21305720067 has 16 divisors (see below), whose sum is σ = 30490705440. Its totient is φ = 13185165312.

The previous prime is 21305720063. The next prime is 21305720077. The reversal of 21305720067 is 76002750312.

It is not a de Polignac number, because 21305720067 - 2² = 21305720063 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21305720063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2857642 + ... + 2865087.

It is an arithmetic number, because the mean of its divisors is an integer number (1905669090).

Almost surely, 2^21305720067 is an apocalyptic number.

21305720067 is a deficient number, since it is larger than the sum of its proper divisors (9184985373).

21305720067 is a wasteful number, since it uses less digits than its factorization.

21305720067 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5722822.

The product of its (nonzero) digits is 17640, while the sum is 33.

The spelling of 21305720067 in words is "twenty-one billion, three hundred five million, seven hundred twenty thousand, sixty-seven".