20120645 has 4 divisors (see below), whose sum is σ = 24144780. Its totient is φ = 16096512.

The previous prime is 20120641. The next prime is 20120651. The reversal of 20120645 is 54602102.

It is a happy number.

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 13060996 + 7059649 = 3614^2 + 2657^2 .

It is a cyclic number.

It is not a de Polignac number, because 20120645 - 2² = 20120641 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20120641) 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, 2012060 + ... + 2012069.

It is an arithmetic number, because the mean of its divisors is an integer number (6036195).

Almost surely, 2^20120645 is an apocalyptic number.

It is an amenable number.

20120645 is a deficient number, since it is larger than the sum of its proper divisors (4024135).

20120645 is an equidigital number, since it uses as much as digits as its factorization.

20120645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4024134.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 20120645 is about 4485.6041956463. The cubic root of 20120645 is about 271.9864693745.

Adding to 20120645 its reverse (54602102), we get a palindrome (74722747).

The spelling of 20120645 in words is "twenty million, one hundred twenty thousand, six hundred forty-five".