21125635012511 has 4 divisors (see below), whose sum is σ = 21471956898024. Its totient is φ = 20779313127000.

The previous prime is 21125635012429. The next prime is 21125635012523. The reversal of 21125635012511 is 11521053652112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21125635012511 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 (21125635012571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 173160942665 + ... + 173160942786.

It is an arithmetic number, because the mean of its divisors is an integer number (5367989224506).

Almost surely, 2^{21125635012511} is an apocalyptic number.

21125635012511 is a deficient number, since it is larger than the sum of its proper divisors (346321885513).

21125635012511 is an equidigital number, since it uses as much as digits as its factorization.

21125635012511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 346321885512.

The product of its (nonzero) digits is 18000, while the sum is 35.

Adding to 21125635012511 its reverse (11521053652112), we get a palindrome (32646688664623).

The spelling of 21125635012511 in words is "twenty-one trillion, one hundred twenty-five billion, six hundred thirty-five million, twelve thousand, five hundred eleven".