21642120057206 has 16 divisors (see below), whose sum is σ = 37497576998160. Its totient is φ = 9258660986880.

The previous prime is 21642120057203. The next prime is 21642120057241. The reversal of 21642120057206 is 60275002124612.

It is a self number, because there is not a number n which added to its sum of digits gives 21642120057206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642120057203) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28933315211 + ... + 28933315958.

It is an arithmetic number, because the mean of its divisors is an integer number (2343598562385).

Almost surely, 2^{21642120057206} is an apocalyptic number.

21642120057206 is a deficient number, since it is larger than the sum of its proper divisors (15855456940954).

21642120057206 is a wasteful number, since it uses less digits than its factorization.

21642120057206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57866631199.

The product of its (nonzero) digits is 80640, while the sum is 38.

The spelling of 21642120057206 in words is "twenty-one trillion, six hundred forty-two billion, one hundred twenty million, fifty-seven thousand, two hundred six".