20978117 has 2 divisors, whose sum is σ = 20978118. Its totient is φ = 20978116.

The previous prime is 20978077. The next prime is 20978123. The reversal of 20978117 is 71187902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14145121 + 6832996 = 3761^2 + 2614^2 .

It is a cyclic number.

It is not a de Polignac number, because 20978117 - 2⁸ = 20977861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20978197) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10489058 + 10489059.

It is an arithmetic number, because the mean of its divisors is an integer number (10489059).

Almost surely, 2^20978117 is an apocalyptic number.

It is an amenable number.

20978117 is a deficient number, since it is larger than the sum of its proper divisors (1).

20978117 is an equidigital number, since it uses as much as digits as its factorization.

20978117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20978117 is about 4580.1874415792. The cubic root of 20978117 is about 275.7965533197.

The spelling of 20978117 in words is "twenty million, nine hundred seventy-eight thousand, one hundred seventeen".