28133651621 has 2 divisors, whose sum is σ = 28133651622. Its totient is φ = 28133651620.

The previous prime is 28133651617. The next prime is 28133651641. The reversal of 28133651621 is 12615633182.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15294268900 + 12839382721 = 123670^2 + 113311^2 .

It is a cyclic number.

It is not a de Polignac number, because 28133651621 - 2² = 28133651617 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28133651641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14066825810 + 14066825811.

It is an arithmetic number, because the mean of its divisors is an integer number (14066825811).

Almost surely, 2^28133651621 is an apocalyptic number.

It is an amenable number.

28133651621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28133651621 is an equidigital number, since it uses as much as digits as its factorization.

28133651621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 38.

The spelling of 28133651621 in words is "twenty-eight billion, one hundred thirty-three million, six hundred fifty-one thousand, six hundred twenty-one".