20644390 has 16 divisors (see below), whose sum is σ = 40018608. Its totient is φ = 7622496.

The previous prime is 20644387. The next prime is 20644391. The reversal of 20644390 is 9344602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644391) 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, 79272 + ... + 79531.

It is an arithmetic number, because the mean of its divisors is an integer number (2501163).

Almost surely, 2^20644390 is an apocalyptic number.

20644390 is a deficient number, since it is larger than the sum of its proper divisors (19374218).

20644390 is a wasteful number, since it uses less digits than its factorization.

20644390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158823.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 20644390 is about 4543.6097983872. The cubic root of 20644390 is about 274.3262404208.

Adding to 20644390 its reverse (9344602), we get a palindrome (29988992).

The spelling of 20644390 in words is "twenty million, six hundred forty-four thousand, three hundred ninety".