20705491 has 2 divisors, whose sum is σ = 20705492. Its totient is φ = 20705490.

The previous prime is 20705471. The next prime is 20705513. The reversal of 20705491 is 19450702.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20705491 is a prime.

It is not a weakly prime, because it can be changed into another prime (20705411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10352745 + 10352746.

It is an arithmetic number, because the mean of its divisors is an integer number (10352746).

Almost surely, 2^20705491 is an apocalyptic number.

20705491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20705491 is an equidigital number, since it uses as much as digits as its factorization.

20705491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 20705491 is about 4550.3286694480. The cubic root of 20705491 is about 274.5966140892.

The spelling of 20705491 in words is "twenty million, seven hundred five thousand, four hundred ninety-one".