21218743355904 has 640 divisors, whose sum is σ = 66515257036800. Its totient is φ = 6668956385280.

The previous prime is 21218743355899. The next prime is 21218743355939. The reversal of 21218743355904 is 40955334781212.

21218743355904 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 8 + 7 + 43 + 3 + 5 + 590 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3045603429 + ... + 3045610395.

It is an arithmetic number, because the mean of its divisors is an integer number (103930089120).

Almost surely, 2^{21218743355904} is an apocalyptic number.

21218743355904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21218743355904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33257628518400).

21218743355904 is an abundant number, since it is smaller than the sum of its proper divisors (45296513680896).

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

21218743355904 is a wasteful number, since it uses less digits than its factorization.

21218743355904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7201 (or 7179 counting only the distinct ones).

The product of its (nonzero) digits is 7257600, while the sum is 54.

The spelling of 21218743355904 in words is "twenty-one trillion, two hundred eighteen billion, seven hundred forty-three million, three hundred fifty-five thousand, nine hundred four".