21147749280 has 864 divisors, whose sum is σ = 89219055744. Its totient is φ = 4538806272.

The previous prime is 21147749251. The next prime is 21147749281. The reversal of 21147749280 is 8294774112.

21147749280 is a `hidden beast` number, since 2 + 1 + 14 + 77 + 492 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21147749281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 134698962 + ... + 134699118.

It is an arithmetic number, because the mean of its divisors is an integer number (103262796).

Almost surely, 2^21147749280 is an apocalyptic number.

21147749280 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 21147749280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44609527872).

21147749280 is an abundant number, since it is smaller than the sum of its proper divisors (68071306464).

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

21147749280 is a wasteful number, since it uses less digits than its factorization.

21147749280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 45.

The spelling of 21147749280 in words is "twenty-one billion, one hundred forty-seven million, seven hundred forty-nine thousand, two hundred eighty".