1994185421 has 2 divisors, whose sum is σ = 1994185422. Its totient is φ = 1994185420.

The previous prime is 1994185381. The next prime is 1994185439. The reversal of 1994185421 is 1245814991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1404375625 + 589809796 = 37475^2 + 24286^2 .

It is an emirp because it is prime and its reverse (1245814991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1994185421 - 2¹⁰ = 1994184397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1994185021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 997092710 + 997092711.

It is an arithmetic number, because the mean of its divisors is an integer number (997092711).

Almost surely, 2^1994185421 is an apocalyptic number.

It is an amenable number.

1994185421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1994185421 is an equidigital number, since it uses as much as digits as its factorization.

1994185421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 44.

The square root of 1994185421 is about 44656.3032616897. The cubic root of 1994185421 is about 1258.6988796479.

The spelling of 1994185421 in words is "one billion, nine hundred ninety-four million, one hundred eighty-five thousand, four hundred twenty-one".