20351645 has 4 divisors (see below), whose sum is σ = 24421980. Its totient is φ = 16281312.

The previous prime is 20351633. The next prime is 20351647. The reversal of 20351645 is 54615302.

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 11363641 + 8988004 = 3371^2 + 2998^2 .

It is a cyclic number.

It is not a de Polignac number, because 20351645 - 2¹⁰ = 20350621 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20351647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2035160 + ... + 2035169.

It is an arithmetic number, because the mean of its divisors is an integer number (6105495).

Almost surely, 2^20351645 is an apocalyptic number.

It is an amenable number.

20351645 is a deficient number, since it is larger than the sum of its proper divisors (4070335).

20351645 is an equidigital number, since it uses as much as digits as its factorization.

20351645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4070334.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 20351645 is about 4511.2797519108. The cubic root of 20351645 is about 273.0233803946.

Adding to 20351645 its reverse (54615302), we get a palindrome (74966947).

The spelling of 20351645 in words is "twenty million, three hundred fifty-one thousand, six hundred forty-five".