21047881155840 has 2592 divisors, whose sum is σ = 95412705373440. Its totient is φ = 4357327011840.

The previous prime is 21047881155839. The next prime is 21047881155901. The reversal of 21047881155840 is 4855118874012.

21047881155840 is a `hidden beast` number, since 2 + 1 + 0 + 4 + 7 + 8 + 81 + 1 + 558 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (2592).

It is a super-2 number, since 2×21047881155840² (a number of 27 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

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 287 ways as a sum of consecutive naturals, for example, 78244911226 + ... + 78244911494.

It is an arithmetic number, because the mean of its divisors is an integer number (36810457320).

Almost surely, 2^{21047881155840} is an apocalyptic number.

21047881155840 is a gapful number since it is divisible by the number (20) 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 21047881155840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47706352686720).

21047881155840 is an abundant number, since it is smaller than the sum of its proper divisors (74364824217600).

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

21047881155840 is an frugal number, since it uses more digits than its factorization.

21047881155840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354 (or 297 counting only the distinct ones).

The product of its (nonzero) digits is 2867200, while the sum is 54.

It can be divided in two parts, 210478 and 81155840, that added together give a palindrome (81366318).

The spelling of 21047881155840 in words is "twenty-one trillion, forty-seven billion, eight hundred eighty-one million, one hundred fifty-five thousand, eight hundred forty".