21621816218004 has 24 divisors (see below), whose sum is σ = 50452488969120. Its totient is φ = 7207045721184.

The previous prime is 21621816217999. The next prime is 21621816218017. The reversal of 21621816218004 is 40081261812612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27895699 + ... + 28660314.

It is an arithmetic number, because the mean of its divisors is an integer number (2102187040380).

Almost surely, 2^{21621816218004} is an apocalyptic number.

It is an amenable number.

21621816218004 is an abundant number, since it is smaller than the sum of its proper divisors (28830672751116).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21621816218004 is a wasteful number, since it uses less digits than its factorization.

21621816218004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56587879 (or 56587877 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 42.

The spelling of 21621816218004 in words is "twenty-one trillion, six hundred twenty-one billion, eight hundred sixteen million, two hundred eighteen thousand, four".