21601616077 has 24 divisors (see below), whose sum is σ = 23681561400. Its totient is φ = 19675611648.

The previous prime is 21601616051. The next prime is 21601616093. The reversal of 21601616077 is 77061610612.

It can be written as a sum of positive squares in 4 ways, for example, as 5698136196 + 15903479881 = 75486^2 + 126109^2 .

It is not a de Polignac number, because 21601616077 - 2¹⁵ = 21601583309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21601616017) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1110249 + ... + 1129537.

It is an arithmetic number, because the mean of its divisors is an integer number (986731725).

Almost surely, 2^21601616077 is an apocalyptic number.

It is an amenable number.

21601616077 is a deficient number, since it is larger than the sum of its proper divisors (2079945323).

21601616077 is a wasteful number, since it uses less digits than its factorization.

21601616077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19437 (or 19414 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 37.

The spelling of 21601616077 in words is "twenty-one billion, six hundred one million, six hundred sixteen thousand, seventy-seven".