20805742 has 4 divisors (see below), whose sum is σ = 31208616. Its totient is φ = 10402870.

The previous prime is 20805721. The next prime is 20805751. The reversal of 20805742 is 24750802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24750802 = 2 ⋅12375401.

It is a self number, because there is not a number n which added to its sum of digits gives 20805742.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5201434 + ... + 5201437.

It is an arithmetic number, because the mean of its divisors is an integer number (7802154).

Almost surely, 2^20805742 is an apocalyptic number.

20805742 is a deficient number, since it is larger than the sum of its proper divisors (10402874).

20805742 is a wasteful number, since it uses less digits than its factorization.

20805742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10402873.

The product of its (nonzero) digits is 4480, while the sum is 28.

The square root of 20805742 is about 4561.3311653507. The cubic root of 20805742 is about 275.0390776424.

The spelling of 20805742 in words is "twenty million, eight hundred five thousand, seven hundred forty-two".