21978188144641 has 8 divisors (see below), whose sum is σ = 22007708276904. Its totient is φ = 21948683658240.

The previous prime is 21978188144611. The next prime is 21978188144681. The reversal of 21978188144641 is 14644188187912.

It can be written as a sum of positive squares in 4 ways, for example, as 7763629296241 + 14214558848400 = 2786329^2 + 3770220^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21978188144641 - 2⁵ = 21978188144609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21978188144611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1098766 + ... + 6720391.

It is an arithmetic number, because the mean of its divisors is an integer number (2750963534613).

Almost surely, 2^{21978188144641} is an apocalyptic number.

It is an amenable number.

21978188144641 is a deficient number, since it is larger than the sum of its proper divisors (29520132263).

21978188144641 is a wasteful number, since it uses less digits than its factorization.

21978188144641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7822931.

The product of its digits is 24772608, while the sum is 64.

The spelling of 21978188144641 in words is "twenty-one trillion, nine hundred seventy-eight billion, one hundred eighty-eight million, one hundred forty-four thousand, six hundred forty-one".