19916081 has 4 divisors (see below), whose sum is σ = 19928052. Its totient is φ = 19904112.

The previous prime is 19916053. The next prime is 19916087. The reversal of 19916081 is 18061991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1288225 + 18627856 = 1135^2 + 4316^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19916081 is a prime.

It is a super-2 number, since 2×19916081² = 793300564797122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19916087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2990 + ... + 6983.

It is an arithmetic number, because the mean of its divisors is an integer number (4982013).

Almost surely, 2^19916081 is an apocalyptic number.

It is an amenable number.

19916081 is a deficient number, since it is larger than the sum of its proper divisors (11971).

19916081 is an equidigital number, since it uses as much as digits as its factorization.

19916081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11970.

The product of its (nonzero) digits is 3888, while the sum is 35.

The square root of 19916081 is about 4462.7436628155. The cubic root of 19916081 is about 271.0615773980.

The spelling of 19916081 in words is "nineteen million, nine hundred sixteen thousand, eighty-one".