20705605 has 4 divisors (see below), whose sum is σ = 24846732. Its totient is φ = 16564480.

The previous prime is 20705593. The next prime is 20705621. The reversal of 20705605 is 50650702.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3006756 + 17698849 = 1734^2 + 4207^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20705605 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20705605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2070556 + ... + 2070565.

It is an arithmetic number, because the mean of its divisors is an integer number (6211683).

Almost surely, 2^20705605 is an apocalyptic number.

It is an amenable number.

20705605 is a deficient number, since it is larger than the sum of its proper divisors (4141127).

20705605 is an equidigital number, since it uses as much as digits as its factorization.

20705605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4141126.

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 20705605 is about 4550.3411959984. The cubic root of 20705605 is about 274.5971180450.

The spelling of 20705605 in words is "twenty million, seven hundred five thousand, six hundred five".