21115515553604 has 24 divisors (see below), whose sum is σ = 39181622597208. Its totient is φ = 9922538124800.

The previous prime is 21115515553597. The next prime is 21115515553631. The reversal of 21115515553604 is 40635551551112.

It can be written as a sum of positive squares in 4 ways, for example, as 6805576562500 + 14309938991104 = 2608750^2 + 3782848^2 .

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, 221437559 + ... + 221532894.

It is an arithmetic number, because the mean of its divisors is an integer number (1632567608217).

Almost surely, 2^{21115515553604} is an apocalyptic number.

It is an amenable number.

21115515553604 is a deficient number, since it is larger than the sum of its proper divisors (18066107043604).

21115515553604 is a wasteful number, since it uses less digits than its factorization.

21115515553604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442971175 (or 442971173 counting only the distinct ones).

The product of its (nonzero) digits is 450000, while the sum is 44.

The spelling of 21115515553604 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred fifty-three thousand, six hundred four".