21100256511 has 16 divisors (see below), whose sum is σ = 30150311424. Its totient is φ = 13091579424.

The previous prime is 21100256509. The next prime is 21100256539. The reversal of 21100256511 is 11565200112.

It is not a de Polignac number, because 21100256511 - 2¹ = 21100256509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100256501) 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, 4129891 + ... + 4134996.

It is an arithmetic number, because the mean of its divisors is an integer number (1884394464).

Almost surely, 2^21100256511 is an apocalyptic number.

21100256511 is a deficient number, since it is larger than the sum of its proper divisors (9050054913).

21100256511 is a wasteful number, since it uses less digits than its factorization.

21100256511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8264950.

The product of its (nonzero) digits is 600, while the sum is 24.

Adding to 21100256511 its reverse (11565200112), we get a palindrome (32665456623).

The spelling of 21100256511 in words is "twenty-one billion, one hundred million, two hundred fifty-six thousand, five hundred eleven".