21544221506 has 16 divisors (see below), whose sum is σ = 32782584600. Its totient is φ = 10616905728.

The previous prime is 21544221493. The next prime is 21544221541. The reversal of 21544221506 is 60512244512.

It can be written as a sum of positive squares in 4 ways, for example, as 18812591281 + 2731630225 = 137159^2 + 52265^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 153350 + ... + 258078.

Almost surely, 2^21544221506 is an apocalyptic number.

21544221506 is a deficient number, since it is larger than the sum of its proper divisors (11238363094).

21544221506 is a wasteful number, since it uses less digits than its factorization.

21544221506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106213.

The product of its (nonzero) digits is 19200, while the sum is 32.

The spelling of 21544221506 in words is "twenty-one billion, five hundred forty-four million, two hundred twenty-one thousand, five hundred six".