21553985104542 has 576 divisors, whose sum is σ = 56066877554688. Its totient is φ = 5961893414400.

The previous prime is 21553985104537. The next prime is 21553985104549. The reversal of 21553985104542 is 24540158935512.

21553985104542 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 3 + 9 + 85 + 10 + 4 + 542 = 666.

It is a super-3 number, since 3×21553985104542³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553985104549) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 57785482668 + ... + 57785483040.

It is an arithmetic number, because the mean of its divisors is an integer number (97338329088).

Almost surely, 2^{21553985104542} is an apocalyptic number.

21553985104542 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21553985104542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28033438777344).

21553985104542 is an abundant number, since it is smaller than the sum of its proper divisors (34512892450146).

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

21553985104542 is a wasteful number, since it uses less digits than its factorization.

21553985104542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 877 (or 863 counting only the distinct ones).

The product of its (nonzero) digits is 8640000, while the sum is 54.

The spelling of 21553985104542 in words is "twenty-one trillion, five hundred fifty-three billion, nine hundred eighty-five million, one hundred four thousand, five hundred forty-two".