27728763721 has 4 divisors (see below), whose sum is σ = 27737685700. Its totient is φ = 27719841744.

The previous prime is 27728763709. The next prime is 27728763731. The reversal of 27728763721 is 12736782772.

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 16952040000 + 10776723721 = 130200^2 + 103811^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27728763721 is a prime.

It is a super-4 number, since 4×27728763721⁴ (a number of 43 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27728763731) 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, 4456326 + ... + 4462543.

It is an arithmetic number, because the mean of its divisors is an integer number (6934421425).

Almost surely, 2^27728763721 is an apocalyptic number.

It is an amenable number.

27728763721 is a deficient number, since it is larger than the sum of its proper divisors (8921979).

27728763721 is an equidigital number, since it uses as much as digits as its factorization.

27728763721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8921978.

The product of its digits is 2765952, while the sum is 52.

The spelling of 27728763721 in words is "twenty-seven billion, seven hundred twenty-eight million, seven hundred sixty-three thousand, seven hundred twenty-one".