21254143549 has 4 divisors (see below), whose sum is σ = 21265255836. Its totient is φ = 21243031264.

The previous prime is 21254143517. The next prime is 21254143553. The reversal of 21254143549 is 94534145212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7508222500 + 13745921049 = 86650^2 + 117243^2 .

It is a cyclic number.

It is not a de Polignac number, because 21254143549 - 2⁵ = 21254143517 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 (21254143949) 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, 5553274 + ... + 5557099.

It is an arithmetic number, because the mean of its divisors is an integer number (5316313959).

Almost surely, 2^21254143549 is an apocalyptic number.

It is an amenable number.

21254143549 is a deficient number, since it is larger than the sum of its proper divisors (11112287).

21254143549 is a wasteful number, since it uses less digits than its factorization.

21254143549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11112286.

The product of its digits is 172800, while the sum is 40.

The spelling of 21254143549 in words is "twenty-one billion, two hundred fifty-four million, one hundred forty-three thousand, five hundred forty-nine".