28356904421 has 2 divisors, whose sum is σ = 28356904422. Its totient is φ = 28356904420.

The previous prime is 28356904397. The next prime is 28356904489. The reversal of 28356904421 is 12440965382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22864464100 + 5492440321 = 151210^2 + 74111^2 .

It is a cyclic number.

It is not a de Polignac number, because 28356904421 - 2⁶ = 28356904357 is a prime.

It is a super-2 number, since 2×28356904421² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28356904021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14178452210 + 14178452211.

It is an arithmetic number, because the mean of its divisors is an integer number (14178452211).

Almost surely, 2^28356904421 is an apocalyptic number.

It is an amenable number.

28356904421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28356904421 is an equidigital number, since it uses as much as digits as its factorization.

28356904421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 414720, while the sum is 44.

The spelling of 28356904421 in words is "twenty-eight billion, three hundred fifty-six million, nine hundred four thousand, four hundred twenty-one".