21310442551 has 4 divisors (see below), whose sum is σ = 21311911152. Its totient is φ = 21308973952.

The previous prime is 21310442533. The next prime is 21310442597. The reversal of 21310442551 is 15524401312.

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

It is a cyclic number.

It is not a de Polignac number, because 21310442551 - 2²³ = 21302053943 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 (21310442501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 712315 + ... + 741628.

It is an arithmetic number, because the mean of its divisors is an integer number (5327977788).

Almost surely, 2^21310442551 is an apocalyptic number.

21310442551 is a deficient number, since it is larger than the sum of its proper divisors (1468601).

21310442551 is a wasteful number, since it uses less digits than its factorization.

21310442551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1468600.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21310442551 its reverse (15524401312), we get a palindrome (36834843863).

The spelling of 21310442551 in words is "twenty-one billion, three hundred ten million, four hundred forty-two thousand, five hundred fifty-one".