20985451056144 has 45 divisors (see below), whose sum is σ = 58730270342653. Its totient is φ = 6995132028096.

The previous prime is 20985451056047. The next prime is 20985451056149. The reversal of 20985451056144 is 44165015458902.

It is a happy number.

The square root of 20985451056144 is 4580988.

It is a perfect power (a square), and thus also a powerful number.

20985451056144 is a `hidden beast` number, since 2 + 0 + 9 + 8 + 5 + 4 + 5 + 10 + 5 + 614 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 150243062544 + 20835207993600 = 387612^2 + 4564560^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20985451056149) 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 8 ways as a sum of consecutive naturals, for example, 54780982 + ... + 55162730.

Almost surely, 2^{20985451056144} is an apocalyptic number.

20985451056144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

20985451056144 is the 4580988-th square number.

It is an amenable number.

20985451056144 is an abundant number, since it is smaller than the sum of its proper divisors (37744819286509).

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

20985451056144 is an frugal number, since it uses more digits than its factorization.

20985451056144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 763512 (or 381754 counting only the distinct ones).

The product of its (nonzero) digits is 6912000, while the sum is 54.

The spelling of 20985451056144 in words is "twenty trillion, nine hundred eighty-five billion, four hundred fifty-one million, fifty-six thousand, one hundred forty-four".