20664191819 has 2 divisors, whose sum is σ = 20664191820. Its totient is φ = 20664191818.

The previous prime is 20664191789. The next prime is 20664191837. The reversal of 20664191819 is 91819146602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20664191819 - 2²⁴ = 20647414603 is a prime.

It is a super-2 number, since 2×20664191819² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20664193819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332095909 + 10332095910.

It is an arithmetic number, because the mean of its divisors is an integer number (10332095910).

Almost surely, 2^20664191819 is an apocalyptic number.

20664191819 is a deficient number, since it is larger than the sum of its proper divisors (1).

20664191819 is an equidigital number, since it uses as much as digits as its factorization.

20664191819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 186624, while the sum is 47.

The spelling of 20664191819 in words is "twenty billion, six hundred sixty-four million, one hundred ninety-one thousand, eight hundred nineteen".