20691819 has 12 divisors (see below), whose sum is σ = 30919200. Its totient is φ = 13318704.

The previous prime is 20691799. The next prime is 20691823. The reversal of 20691819 is 91819602.

It is not a de Polignac number, because 20691819 - 2⁷ = 20691691 is a prime.

It is a super-2 number, since 2×20691819² = 856302747057522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20691859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39379 + ... + 39900.

It is an arithmetic number, because the mean of its divisors is an integer number (2576600).

Almost surely, 2^20691819 is an apocalyptic number.

20691819 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20691819 is a deficient number, since it is larger than the sum of its proper divisors (10227381).

20691819 is a wasteful number, since it uses less digits than its factorization.

20691819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79314 (or 79311 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 20691819 is about 4548.8261123063. The cubic root of 20691819 is about 274.5361613404.

The spelling of 20691819 in words is "twenty million, six hundred ninety-one thousand, eight hundred nineteen".