21144235513 has 4 divisors (see below), whose sum is σ = 21145862800. Its totient is φ = 21142608228.

The previous prime is 21144235499. The next prime is 21144235531. The reversal of 21144235513 is 31553244112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21144235513 - 2⁹ = 21144235001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21144235543) 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, 793995 + ... + 820192.

It is an arithmetic number, because the mean of its divisors is an integer number (5286465700).

Almost surely, 2^21144235513 is an apocalyptic number.

It is an amenable number.

21144235513 is a deficient number, since it is larger than the sum of its proper divisors (1627287).

21144235513 is a wasteful number, since it uses less digits than its factorization.

21144235513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627286.

The product of its digits is 14400, while the sum is 31.

Adding to 21144235513 its reverse (31553244112), we get a palindrome (52697479625).

It can be divided in two parts, 2114423 and 5513, that added together give a square (2119936 = 1456²).

The spelling of 21144235513 in words is "twenty-one billion, one hundred forty-four million, two hundred thirty-five thousand, five hundred thirteen".