27942799921 has 9 divisors (see below), whose sum is σ = 29686200961. Its totient is φ = 26296431232.

The previous prime is 27942799919. The next prime is 27942799943. The reversal of 27942799921 is 12999724972.

The square root of 27942799921 is 167161.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 2699945521 + 25242854400 = 51961^2 + 158880^2 .

It is not a de Polignac number, because 27942799921 - 2¹ = 27942799919 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 27942799921.

It is not an unprimeable number, because it can be changed into a prime (27942719921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2836821 + ... + 2846653.

Almost surely, 2^27942799921 is an apocalyptic number.

27942799921 is the 167161-st square number.

27942799921 is the 83581-st centered octagonal number.

It is an amenable number.

27942799921 is a deficient number, since it is larger than the sum of its proper divisors (1743401040).

27942799921 is an frugal number, since it uses more digits than its factorization.

27942799921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19700 (or 9850 counting only the distinct ones).

The product of its digits is 10287648, while the sum is 61.

The spelling of 27942799921 in words is "twenty-seven billion, nine hundred forty-two million, seven hundred ninety-nine thousand, nine hundred twenty-one".