20705551 has 4 divisors (see below), whose sum is σ = 21373504. Its totient is φ = 20037600.

The previous prime is 20705549. The next prime is 20705557. The reversal of 20705551 is 15550702.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20705551 - 2¹ = 20705549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20705557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333930 + ... + 333991.

It is an arithmetic number, because the mean of its divisors is an integer number (5343376).

Almost surely, 2^20705551 is an apocalyptic number.

20705551 is a deficient number, since it is larger than the sum of its proper divisors (667953).

20705551 is an equidigital number, since it uses as much as digits as its factorization.

20705551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 667952.

The product of its (nonzero) digits is 1750, while the sum is 25.

The square root of 20705551 is about 4550.3352623735. The cubic root of 20705551 is about 274.5968793293.

The spelling of 20705551 in words is "twenty million, seven hundred five thousand, five hundred fifty-one".