21147420784 has 80 divisors (see below), whose sum is σ = 49323827200. Its totient is φ = 8770749120.

The previous prime is 21147420731. The next prime is 21147420839. The reversal of 21147420784 is 48702474112.

It is a super-3 number, since 3×21147420784³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107977 + ... + 232279.

It is an arithmetic number, because the mean of its divisors is an integer number (616547840).

Almost surely, 2^21147420784 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21147420784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24661913600).

21147420784 is an abundant number, since it is smaller than the sum of its proper divisors (28176406416).

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

21147420784 is a wasteful number, since it uses less digits than its factorization.

21147420784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124363 (or 124343 counting only the distinct ones).

The product of its (nonzero) digits is 100352, while the sum is 40.

Adding to 21147420784 its reverse (48702474112), we get a palindrome (69849894896).

The spelling of 21147420784 in words is "twenty-one billion, one hundred forty-seven million, four hundred twenty thousand, seven hundred eighty-four".