20751845 has 4 divisors (see below), whose sum is σ = 24902220. Its totient is φ = 16601472.

The previous prime is 20751839. The next prime is 20751847. The reversal of 20751845 is 54815702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54815702 = 2 ⋅27407851.

It can be written as a sum of positive squares in 2 ways, for example, as 4502884 + 16248961 = 2122^2 + 4031^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20751845 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20751847) 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, 2075180 + ... + 2075189.

It is an arithmetic number, because the mean of its divisors is an integer number (6225555).

Almost surely, 2^20751845 is an apocalyptic number.

It is an amenable number.

20751845 is a deficient number, since it is larger than the sum of its proper divisors (4150375).

20751845 is an equidigital number, since it uses as much as digits as its factorization.

20751845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4150374.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 20751845 is about 4555.4193001303. The cubic root of 20751845 is about 274.8013772375.

The spelling of 20751845 in words is "twenty million, seven hundred fifty-one thousand, eight hundred forty-five".