28755637661 has 4 divisors (see below), whose sum is σ = 28756645500. Its totient is φ = 28754629824.

The previous prime is 28755637657. The next prime is 28755637699. The reversal of 28755637661 is 16673655782.

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 6463356025 + 22292281636 = 80395^2 + 149306^2 .

It is a cyclic number.

It is not a de Polignac number, because 28755637661 - 2² = 28755637657 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28755637597 and 28755637606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28755631661) 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, 459836 + ... + 518613.

It is an arithmetic number, because the mean of its divisors is an integer number (7189161375).

Almost surely, 2^28755637661 is an apocalyptic number.

It is an amenable number.

28755637661 is a deficient number, since it is larger than the sum of its proper divisors (1007839).

28755637661 is an equidigital number, since it uses as much as digits as its factorization.

28755637661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1007838.

The product of its digits is 12700800, while the sum is 56.

The spelling of 28755637661 in words is "twenty-eight billion, seven hundred fifty-five million, six hundred thirty-seven thousand, six hundred sixty-one".