21616121656541 has 8 divisors (see below), whose sum is σ = 21626477950464. Its totient is φ = 21605766611440.

The previous prime is 21616121656531. The next prime is 21616121656603. The reversal of 21616121656541 is 14565612161612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21616121656541 - 2³⁰ = 21615047914717 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616121656501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35283011 + ... + 35890431.

It is an arithmetic number, because the mean of its divisors is an integer number (2703309743808).

Almost surely, 2^{21616121656541} is an apocalyptic number.

It is an amenable number.

21616121656541 is a deficient number, since it is larger than the sum of its proper divisors (10356293923).

21616121656541 is a wasteful number, since it uses less digits than its factorization.

21616121656541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 624411.

The product of its digits is 518400, while the sum is 47.

The spelling of 21616121656541 in words is "twenty-one trillion, six hundred sixteen billion, one hundred twenty-one million, six hundred fifty-six thousand, five hundred forty-one".