21945603578 has 4 divisors (see below), whose sum is σ = 32918405370. Its totient is φ = 10972801788.

The previous prime is 21945603541. The next prime is 21945603583. The reversal of 21945603578 is 87530654912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12278191249 + 9667412329 = 110807^2 + 98323^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5486400893 + ... + 5486400896.

It is a 2-persistent number, because it is pandigital, and so is 2⋅21945603578 = 43891207156, but 3⋅21945603578 = 65836810734 is not.

Almost surely, 2^21945603578 is an apocalyptic number.

21945603578 is a deficient number, since it is larger than the sum of its proper divisors (10972801792).

21945603578 is a wasteful number, since it uses less digits than its factorization.

21945603578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10972801791.

The product of its (nonzero) digits is 1814400, while the sum is 50.

The spelling of 21945603578 in words is "twenty-one billion, nine hundred forty-five million, six hundred three thousand, five hundred seventy-eight".