20638819 has 2 divisors, whose sum is σ = 20638820. Its totient is φ = 20638818.

The previous prime is 20638811. The next prime is 20638853. The reversal of 20638819 is 91883602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20638819 - 2³ = 20638811 is a prime.

It is a super-2 number, since 2×20638819² = 851921699429522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20638811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10319409 + 10319410.

It is an arithmetic number, because the mean of its divisors is an integer number (10319410).

Almost surely, 2^20638819 is an apocalyptic number.

20638819 is a deficient number, since it is larger than the sum of its proper divisors (1).

20638819 is an equidigital number, since it uses as much as digits as its factorization.

20638819 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 37.

The square root of 20638819 is about 4542.9966982158. The cubic root of 20638819 is about 274.3015620623.

The spelling of 20638819 in words is "twenty million, six hundred thirty-eight thousand, eight hundred nineteen".