20509380 has 72 divisors (see below), whose sum is σ = 64373400. Its totient is φ = 5279232.

The previous prime is 20509373. The next prime is 20509421. The reversal of 20509380 is 8390502.

It can be written as a sum of positive squares in 4 ways, for example, as 367236 + 20142144 = 606^2 + 4488^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3256 + ... + 7184.

It is an arithmetic number, because the mean of its divisors is an integer number (894075).

Almost surely, 2^20509380 is an apocalyptic number.

20509380 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 20509380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32186700).

20509380 is an abundant number, since it is smaller than the sum of its proper divisors (43864020).

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

20509380 is a wasteful number, since it uses less digits than its factorization.

20509380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3973 (or 3968 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 20509380 is about 4528.7282983195. The cubic root of 20509380 is about 273.7269199282.

Adding to 20509380 its reverse (8390502), we get a palindrome (28899882).

The spelling of 20509380 in words is "twenty million, five hundred nine thousand, three hundred eighty".