21012016605553 has 16 divisors (see below), whose sum is σ = 21510418890240. Its totient is φ = 20517441369984.

The previous prime is 21012016605529. The next prime is 21012016605647. The reversal of 21012016605553 is 35550661021012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21012016605553 - 2⁴¹ = 18812993350001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012016605053) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42812613 + ... + 43300621.

It is an arithmetic number, because the mean of its divisors is an integer number (1344401180640).

Almost surely, 2^{21012016605553} is an apocalyptic number.

It is an amenable number.

21012016605553 is a deficient number, since it is larger than the sum of its proper divisors (498402284687).

21012016605553 is a wasteful number, since it uses less digits than its factorization.

21012016605553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491928.

The product of its (nonzero) digits is 54000, while the sum is 37.

Adding to 21012016605553 its reverse (35550661021012), we get a palindrome (56562677626565).

The spelling of 21012016605553 in words is "twenty-one trillion, twelve billion, sixteen million, six hundred five thousand, five hundred fifty-three".