20820977 has 2 divisors, whose sum is σ = 20820978. Its totient is φ = 20820976.

The previous prime is 20820967. The next prime is 20821007. The reversal of 20820977 is 77902802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20511841 + 309136 = 4529^2 + 556^2 .

It is a cyclic number.

It is not a de Polignac number, because 20820977 - 2⁸ = 20820721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20820967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10410488 + 10410489.

It is an arithmetic number, because the mean of its divisors is an integer number (10410489).

Almost surely, 2^20820977 is an apocalyptic number.

It is an amenable number.

20820977 is a deficient number, since it is larger than the sum of its proper divisors (1).

20820977 is an equidigital number, since it uses as much as digits as its factorization.

20820977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 20820977 is about 4563.0008766162. Note that the first 3 decimals coincide. The cubic root of 20820977 is about 275.1061936978.

The spelling of 20820977 in words is "twenty million, eight hundred twenty thousand, nine hundred seventy-seven".