21144155431 has 4 divisors (see below), whose sum is σ = 24164749072. Its totient is φ = 18123561792.

The previous prime is 21144155419. The next prime is 21144155447. The reversal of 21144155431 is 13455144112.

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

It is not a de Polignac number, because 21144155431 - 2¹¹ = 21144153383 is a prime.

It is a super-2 number, since 2×21144155431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21144155393 and 21144155402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144155401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1510296810 + ... + 1510296823.

It is an arithmetic number, because the mean of its divisors is an integer number (6041187268).

Almost surely, 2^21144155431 is an apocalyptic number.

21144155431 is a deficient number, since it is larger than the sum of its proper divisors (3020593641).

21144155431 is an equidigital number, since it uses as much as digits as its factorization.

21144155431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3020593640.

The product of its digits is 9600, while the sum is 31.

Adding to 21144155431 its reverse (13455144112), we get a palindrome (34599299543).

The spelling of 21144155431 in words is "twenty-one billion, one hundred forty-four million, one hundred fifty-five thousand, four hundred thirty-one".