19909081 has 2 divisors, whose sum is σ = 19909082. Its totient is φ = 19909080.

The previous prime is 19909073. The next prime is 19909103. The reversal of 19909081 is 18090991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19360000 + 549081 = 4400^2 + 741^2 .

It is a cyclic number.

It is not a de Polignac number, because 19909081 - 2³ = 19909073 is a prime.

It is a super-2 number, since 2×19909081² = 792743012529122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 19909081.

It is not a weakly prime, because it can be changed into another prime (19909061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9954540 + 9954541.

It is an arithmetic number, because the mean of its divisors is an integer number (9954541).

Almost surely, 2^19909081 is an apocalyptic number.

It is an amenable number.

19909081 is a deficient number, since it is larger than the sum of its proper divisors (1).

19909081 is an equidigital number, since it uses as much as digits as its factorization.

19909081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 19909081 is about 4461.9593229881. The cubic root of 19909081 is about 271.0298165747.

The spelling of 19909081 in words is "nineteen million, nine hundred nine thousand, eighty-one".