20851697 has 2 divisors, whose sum is σ = 20851698. Its totient is φ = 20851696.

The previous prime is 20851693. The next prime is 20851711. The reversal of 20851697 is 79615802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20421361 + 430336 = 4519^2 + 656^2 .

It is a cyclic number.

It is not a de Polignac number, because 20851697 - 2² = 20851693 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20851697.

It is not a weakly prime, because it can be changed into another prime (20851693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425848 + 10425849.

It is an arithmetic number, because the mean of its divisors is an integer number (10425849).

Almost surely, 2^20851697 is an apocalyptic number.

It is an amenable number.

20851697 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851697 is an equidigital number, since it uses as much as digits as its factorization.

20851697 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 20851697 is about 4566.3658416732. The cubic root of 20851697 is about 275.2414276535.

The spelling of 20851697 in words is "twenty million, eight hundred fifty-one thousand, six hundred ninety-seven".