21201721834546 has 16 divisors (see below), whose sum is σ = 34894268417088. Its totient is φ = 9581440238800.

The previous prime is 21201721834499. The next prime is 21201721834547. The reversal of 21201721834546 is 64543812710212.

It is a happy number.

It is a super-2 number, since 2×21201721834546² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21201721834496 and 21201721834505.

It is not an unprimeable number, because it can be changed into a prime (21201721834547) 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 7 ways as a sum of consecutive naturals, for example, 2785298590 + ... + 2785306201.

It is an arithmetic number, because the mean of its divisors is an integer number (2180891776068).

Almost surely, 2^{21201721834546} is an apocalyptic number.

21201721834546 is a deficient number, since it is larger than the sum of its proper divisors (13692546582542).

21201721834546 is a wasteful number, since it uses less digits than its factorization.

21201721834546 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5570604977.

The product of its (nonzero) digits is 645120, while the sum is 46.

The spelling of 21201721834546 in words is "twenty-one trillion, two hundred one billion, seven hundred twenty-one million, eight hundred thirty-four thousand, five hundred forty-six".