20051645 has 8 divisors (see below), whose sum is σ = 24185304. Its totient is φ = 15959104.

The previous prime is 20051641. The next prime is 20051659. The reversal of 20051645 is 54615002.

It can be written as a sum of positive squares in 4 ways, for example, as 8031556 + 12020089 = 2834^2 + 3467^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20051645 - 2² = 20051641 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20051645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20051641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9194 + ... + 11163.

It is an arithmetic number, because the mean of its divisors is an integer number (3023163).

Almost surely, 2^20051645 is an apocalyptic number.

It is an amenable number.

20051645 is a deficient number, since it is larger than the sum of its proper divisors (4133659).

20051645 is a wasteful number, since it uses less digits than its factorization.

20051645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20559.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 20051645 is about 4477.9063188057. The cubic root of 20051645 is about 271.6752043352.

Adding to 20051645 its reverse (54615002), we get a palindrome (74666647).

The spelling of 20051645 in words is "twenty million, fifty-one thousand, six hundred forty-five".