20645380 has 96 divisors (see below), whose sum is σ = 52641792. Its totient is φ = 6652800.

The previous prime is 20645347. The next prime is 20645399. The reversal of 20645380 is 8354602.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 290745 + ... + 290815.

It is an arithmetic number, because the mean of its divisors is an integer number (548352).

Almost surely, 2^20645380 is an apocalyptic number.

20645380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20645380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26320896).

20645380 is an abundant number, since it is smaller than the sum of its proper divisors (31996412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20645380 is a wasteful number, since it uses less digits than its factorization.

20645380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185 (or 183 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 20645380 is about 4543.7187412955. The cubic root of 20645380 is about 274.3306254481.

Adding to 20645380 its reverse (8354602), we get a palindrome (28999982).

It can be divided in two parts, 20645 and 380, that added together give a square (21025 = 145²).

The spelling of 20645380 in words is "twenty million, six hundred forty-five thousand, three hundred eighty".