20847745 has 4 divisors (see below), whose sum is σ = 25017300. Its totient is φ = 16678192.

The previous prime is 20847737. The next prime is 20847751. The reversal of 20847745 is 54774802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54774802 = 2 ⋅27387401.

It can be written as a sum of positive squares in 2 ways, for example, as 9511056 + 11336689 = 3084^2 + 3367^2 .

It is a cyclic number.

It is not a de Polignac number, because 20847745 - 2³ = 20847737 is a prime.

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, 2084770 + ... + 2084779.

It is an arithmetic number, because the mean of its divisors is an integer number (6254325).

Almost surely, 2^20847745 is an apocalyptic number.

It is an amenable number.

20847745 is a deficient number, since it is larger than the sum of its proper divisors (4169555).

20847745 is an equidigital number, since it uses as much as digits as its factorization.

20847745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4169554.

The product of its (nonzero) digits is 62720, while the sum is 37.

The square root of 20847745 is about 4565.9330919320. The cubic root of 20847745 is about 275.2240378163.

The spelling of 20847745 in words is "twenty million, eight hundred forty-seven thousand, seven hundred forty-five".