21616565270401 has 4 divisors (see below), whose sum is σ = 21616587816772. Its totient is φ = 21616542724032.

The previous prime is 21616565270369. The next prime is 21616565270411. The reversal of 21616565270401 is 10407256561612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4948738379776 + 16667826890625 = 2224576^2 + 4082625^2 .

It is a cyclic number.

It is not a de Polignac number, because 21616565270401 - 2⁵ = 21616565270369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21616565270411) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9768060 + ... + 11774893.

It is an arithmetic number, because the mean of its divisors is an integer number (5404146954193).

Almost surely, 2^{21616565270401} is an apocalyptic number.

It is an amenable number.

21616565270401 is a deficient number, since it is larger than the sum of its proper divisors (22546371).

21616565270401 is a wasteful number, since it uses less digits than its factorization.

21616565270401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22546370.

The product of its (nonzero) digits is 604800, while the sum is 46.

The spelling of 21616565270401 in words is "twenty-one trillion, six hundred sixteen billion, five hundred sixty-five million, two hundred seventy thousand, four hundred one".