21205116145 has 16 divisors (see below), whose sum is σ = 25775922240. Its totient is φ = 16745256000.

The previous prime is 21205116113. The next prime is 21205116151. The reversal of 21205116145 is 54161150212.

It is not a de Polignac number, because 21205116145 - 2⁵ = 21205116113 is a prime.

It is a super-2 number, since 2×21205116145² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103726 + ... + 230584.

It is an arithmetic number, because the mean of its divisors is an integer number (1610995140).

Almost surely, 2^21205116145 is an apocalyptic number.

It is an amenable number.

21205116145 is a deficient number, since it is larger than the sum of its proper divisors (4570806095).

21205116145 is a wasteful number, since it uses less digits than its factorization.

21205116145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127296.

The product of its (nonzero) digits is 2400, while the sum is 28.

Adding to 21205116145 its reverse (54161150212), we get a palindrome (75366266357).

The spelling of 21205116145 in words is "twenty-one billion, two hundred five million, one hundred sixteen thousand, one hundred forty-five".