20820691 has 2 divisors, whose sum is σ = 20820692. Its totient is φ = 20820690.

The previous prime is 20820689. The next prime is 20820697. The reversal of 20820691 is 19602802.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20820691 - 2¹ = 20820689 is a prime.

Together with 20820689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20820697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10410345 + 10410346.

It is an arithmetic number, because the mean of its divisors is an integer number (10410346).

Almost surely, 2^20820691 is an apocalyptic number.

20820691 is a deficient number, since it is larger than the sum of its proper divisors (1).

20820691 is an equidigital number, since it uses as much as digits as its factorization.

20820691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 20820691 is about 4562.9695374832. The cubic root of 20820691 is about 275.1049340590.

The spelling of 20820691 in words is "twenty million, eight hundred twenty thousand, six hundred ninety-one".