21566647240 has 64 divisors (see below), whose sum is σ = 48980828160. Its totient is φ = 8545824000.

The previous prime is 21566647211. The next prime is 21566647247. The reversal of 21566647240 is 4274666512.

It is not an unprimeable number, because it can be changed into a prime (21566647247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3812254 + ... + 3817906.

It is an arithmetic number, because the mean of its divisors is an integer number (765325440).

Almost surely, 2^21566647240 is an apocalyptic number.

21566647240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21566647240 is an abundant number, since it is smaller than the sum of its proper divisors (27414180920).

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

21566647240 is a wasteful number, since it uses less digits than its factorization.

21566647240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6542 (or 6538 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 43.

It can be divided in two parts, 215666472 and 40, that added together give a palindrome (215666512).

The spelling of 21566647240 in words is "twenty-one billion, five hundred sixty-six million, six hundred forty-seven thousand, two hundred forty".