21543124154 has 4 divisors (see below), whose sum is σ = 32314686234. Its totient is φ = 10771562076.

The previous prime is 21543124069. The next prime is 21543124157. The reversal of 21543124154 is 45142134512.

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

It can be written as a sum of positive squares in only one way, i.e., 17378357929 + 4164766225 = 131827^2 + 64535^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21543124154.

It is not an unprimeable number, because it can be changed into a prime (21543124157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5385781037 + ... + 5385781040.

Almost surely, 2^21543124154 is an apocalyptic number.

21543124154 is a deficient number, since it is larger than the sum of its proper divisors (10771562080).

21543124154 is a wasteful number, since it uses less digits than its factorization.

21543124154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10771562079.

The product of its digits is 19200, while the sum is 32.

Adding to 21543124154 its reverse (45142134512), we get a palindrome (66685258666).

The spelling of 21543124154 in words is "twenty-one billion, five hundred forty-three million, one hundred twenty-four thousand, one hundred fifty-four".