21115516445564 has 24 divisors (see below), whose sum is σ = 37109494939776. Its totient is φ = 10512882270000.

The previous prime is 21115516445549. The next prime is 21115516445581. The reversal of 21115516445564 is 46554461551112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8758712 + ... + 10906239.

It is an arithmetic number, because the mean of its divisors is an integer number (1546228955824).

Almost surely, 2^{21115516445564} is an apocalyptic number.

It is an amenable number.

21115516445564 is a deficient number, since it is larger than the sum of its proper divisors (15993978494212).

21115516445564 is a wasteful number, since it uses less digits than its factorization.

21115516445564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19666097 (or 19666095 counting only the distinct ones).

The product of its digits is 2880000, while the sum is 50.

Adding to 21115516445564 its reverse (46554461551112), we get a palindrome (67669977996676).

The spelling of 21115516445564 in words is "twenty-one trillion, one hundred fifteen billion, five hundred sixteen million, four hundred forty-five thousand, five hundred sixty-four".