28211651861 has 12 divisors (see below), whose sum is σ = 30582028332. Its totient is φ = 25934622336.

The previous prime is 28211651837. The next prime is 28211651863. The reversal of 28211651861 is 16815611282.

It can be written as a sum of positive squares in 2 ways, for example, as 25766349361 + 2445302500 = 160519^2 + 49450^2 .

It is a de Polignac number, because none of the positive numbers 2^k-28211651861 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 (28211651863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 417326 + ... + 480191.

It is an arithmetic number, because the mean of its divisors is an integer number (2548502361).

Almost surely, 2^28211651861 is an apocalyptic number.

It is an amenable number.

28211651861 is a deficient number, since it is larger than the sum of its proper divisors (2370376471).

28211651861 is an equidigital number, since it uses as much as digits as its factorization.

28211651861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 897620 (or 897577 counting only the distinct ones).

The product of its digits is 46080, while the sum is 41.

The spelling of 28211651861 in words is "twenty-eight billion, two hundred eleven million, six hundred fifty-one thousand, eight hundred sixty-one".