28394517421 has 2 divisors, whose sum is σ = 28394517422. Its totient is φ = 28394517420.

The previous prime is 28394517341. The next prime is 28394517457. The reversal of 28394517421 is 12471549382.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27751894921 + 642622500 = 166589^2 + 25350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28394517421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28394517521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14197258710 + 14197258711.

It is an arithmetic number, because the mean of its divisors is an integer number (14197258711).

Almost surely, 2^28394517421 is an apocalyptic number.

It is an amenable number.

28394517421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28394517421 is an equidigital number, since it uses as much as digits as its factorization.

28394517421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 483840, while the sum is 46.

The spelling of 28394517421 in words is "twenty-eight billion, three hundred ninety-four million, five hundred seventeen thousand, four hundred twenty-one".