20723405 has 4 divisors (see below), whose sum is σ = 24868092. Its totient is φ = 16578720.

The previous prime is 20723401. The next prime is 20723411. The reversal of 20723405 is 50432702.

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 4571044 + 16152361 = 2138^2 + 4019^2 .

It is not a de Polignac number, because 20723405 - 2² = 20723401 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 (20723401) 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, 2072336 + ... + 2072345.

It is an arithmetic number, because the mean of its divisors is an integer number (6217023).

Almost surely, 2^20723405 is an apocalyptic number.

It is an amenable number.

20723405 is a deficient number, since it is larger than the sum of its proper divisors (4144687).

20723405 is an equidigital number, since it uses as much as digits as its factorization.

20723405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4144686.

The product of its (nonzero) digits is 1680, while the sum is 23.

The square root of 20723405 is about 4552.2966731091. The cubic root of 20723405 is about 274.6757831975.

The spelling of 20723405 in words is "twenty million, seven hundred twenty-three thousand, four hundred five".