1994420081 has 2 divisors, whose sum is σ = 1994420082. Its totient is φ = 1994420080.

The previous prime is 1994420047. The next prime is 1994420089. The reversal of 1994420081 is 1800244991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1905759025 + 88661056 = 43655^2 + 9416^2 .

It is an emirp because it is prime and its reverse (1800244991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1994420081 is a prime.

It is a super-2 number, since 2×1994420081² = 7955422918992093122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1994420089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 997210040 + 997210041.

It is an arithmetic number, because the mean of its divisors is an integer number (997210041).

Almost surely, 2^1994420081 is an apocalyptic number.

It is an amenable number.

1994420081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1994420081 is an equidigital number, since it uses as much as digits as its factorization.

1994420081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 1994420081 is about 44658.9305850465. The cubic root of 1994420081 is about 1258.7482489612.

The spelling of 1994420081 in words is "one billion, nine hundred ninety-four million, four hundred twenty thousand, eighty-one".