21809541601 has 8 divisors (see below), whose sum is σ = 21930263784. Its totient is φ = 21688920960.

The previous prime is 21809541577. The next prime is 21809541619. The reversal of 21809541601 is 10614590812.

It can be written as a sum of positive squares in 4 ways, for example, as 6380175376 + 15429366225 = 79876^2 + 124215^2 .

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 21809541601 - 2¹⁹ = 21809017313 is a prime.

It is a super-2 number, since 2×21809541601² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21809541641) 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, 427581 + ... + 475861.

It is an arithmetic number, because the mean of its divisors is an integer number (2741282973).

Almost surely, 2^21809541601 is an apocalyptic number.

It is an amenable number.

21809541601 is a deficient number, since it is larger than the sum of its proper divisors (120722183).

21809541601 is a wasteful number, since it uses less digits than its factorization.

21809541601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50771.

The product of its (nonzero) digits is 17280, while the sum is 37.

The spelling of 21809541601 in words is "twenty-one billion, eight hundred nine million, five hundred forty-one thousand, six hundred one".