20840471 has 2 divisors, whose sum is σ = 20840472. Its totient is φ = 20840470.

The previous prime is 20840459. The next prime is 20840489. The reversal of 20840471 is 17404802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20840471 - 2²² = 16646167 is a prime.

It is a super-3 number, since 3×20840471³ (a number of 23 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20840471.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20845471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420235 + 10420236.

It is an arithmetic number, because the mean of its divisors is an integer number (10420236).

Almost surely, 2^20840471 is an apocalyptic number.

20840471 is a deficient number, since it is larger than the sum of its proper divisors (1).

20840471 is an equidigital number, since it uses as much as digits as its factorization.

20840471 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 20840471 is about 4565.1364711255. The cubic root of 20840471 is about 275.1920245613.

The spelling of 20840471 in words is "twenty million, eight hundred forty thousand, four hundred seventy-one".