21018221351904 has 576 divisors, whose sum is σ = 70429289011200. Its totient is φ = 5451038208000.

The previous prime is 21018221351903. The next prime is 21018221351921. The reversal of 21018221351904 is 40915312281012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21018221351903) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 279798702 + ... + 279873810.

It is an arithmetic number, because the mean of its divisors is an integer number (122273071200).

Almost surely, 2^{21018221351904} is an apocalyptic number.

21018221351904 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 21018221351904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35214644505600).

21018221351904 is an abundant number, since it is smaller than the sum of its proper divisors (49411067659296).

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

21018221351904 is a wasteful number, since it uses less digits than its factorization.

21018221351904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75287 (or 75272 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 39.

The spelling of 21018221351904 in words is "twenty-one trillion, eighteen billion, two hundred twenty-one million, three hundred fifty-one thousand, nine hundred four".