20402705 has 4 divisors (see below), whose sum is σ = 24483252. Its totient is φ = 16322160.

The previous prime is 20402693. The next prime is 20402717. The reversal of 20402705 is 50720402.

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

It is an interprime number because it is at equal distance from previous prime (20402693) and next prime (20402717).

It can be written as a sum of positive squares in 2 ways, for example, as 14167696 + 6235009 = 3764^2 + 2497^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20402705 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2040266 + ... + 2040275.

It is an arithmetic number, because the mean of its divisors is an integer number (6120813).

Almost surely, 2^20402705 is an apocalyptic number.

It is an amenable number.

20402705 is a deficient number, since it is larger than the sum of its proper divisors (4080547).

20402705 is an equidigital number, since it uses as much as digits as its factorization.

20402705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4080546.

The product of its (nonzero) digits is 560, while the sum is 20.

The square root of 20402705 is about 4516.9353548617. The cubic root of 20402705 is about 273.2515180804.

The spelling of 20402705 in words is "twenty million, four hundred two thousand, seven hundred five".