21154144365 has 12 divisors (see below), whose sum is σ = 36667183644. Its totient is φ = 11282210304.

The previous prime is 21154144357. The next prime is 21154144387. The reversal of 21154144365 is 56344145112.

21154144365 is a `hidden beast` number, since 2 + 1 + 154 + 1 + 443 + 65 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 10748920329 + 10405224036 = 103677^2 + 102006^2 .

It is not a de Polignac number, because 21154144365 - 2³ = 21154144357 is a prime.

It is a super-2 number, since 2×21154144365² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 235046004 + ... + 235046093.

It is an arithmetic number, because the mean of its divisors is an integer number (3055598637).

Almost surely, 2^21154144365 is an apocalyptic number.

It is an amenable number.

21154144365 is a deficient number, since it is larger than the sum of its proper divisors (15513039279).

21154144365 is a wasteful number, since it uses less digits than its factorization.

21154144365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 470092108 (or 470092105 counting only the distinct ones).

The product of its digits is 57600, while the sum is 36.

Adding to 21154144365 its reverse (56344145112), we get a palindrome (77498289477).

The spelling of 21154144365 in words is "twenty-one billion, one hundred fifty-four million, one hundred forty-four thousand, three hundred sixty-five".