21551526144 has 252 divisors, whose sum is σ = 68302894716. Its totient is φ = 6760267776.

The previous prime is 21551526137. The next prime is 21551526167. The reversal of 21551526144 is 44162515512.

21551526144 is a `hidden beast` number, since 2 + 1 + 551 + 5 + 2 + 61 + 44 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 9032601600 + 12518924544 = 95040^2 + 111888^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21551526099 and 21551526108.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 3169212 + ... + 3176004.

It is an arithmetic number, because the mean of its divisors is an integer number (271043233).

Almost surely, 2^21551526144 is an apocalyptic number.

21551526144 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 21551526144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34151447358).

21551526144 is an abundant number, since it is smaller than the sum of its proper divisors (46751368572).

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

21551526144 is an frugal number, since it uses more digits than its factorization.

21551526144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6844 (or 6815 counting only the distinct ones).

The product of its digits is 48000, while the sum is 36.

The spelling of 21551526144 in words is "twenty-one billion, five hundred fifty-one million, five hundred twenty-six thousand, one hundred forty-four".