21616426305661 has 16 divisors (see below), whose sum is σ = 23702341436928. Its totient is φ = 19550651198400.

The previous prime is 21616426305653. The next prime is 21616426305709. The reversal of 21616426305661 is 16650362461612.

It is a cyclic number.

It is not a de Polignac number, because 21616426305661 - 2³ = 21616426305653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616426395661) 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, 49778671 + ... + 50211043.

It is an arithmetic number, because the mean of its divisors is an integer number (1481396339808).

Almost surely, 2^{21616426305661} is an apocalyptic number.

It is an amenable number.

21616426305661 is a deficient number, since it is larger than the sum of its proper divisors (2085915131267).

21616426305661 is a wasteful number, since it uses less digits than its factorization.

21616426305661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455652.

The product of its (nonzero) digits is 1866240, while the sum is 49.

The spelling of 21616426305661 in words is "twenty-one trillion, six hundred sixteen billion, four hundred twenty-six million, three hundred five thousand, six hundred sixty-one".