20381540 has 12 divisors (see below), whose sum is σ = 42801276. Its totient is φ = 8152608.

The previous prime is 20381489. The next prime is 20381549. The reversal of 20381540 is 4518302.

It can be written as a sum of positive squares in 2 ways, for example, as 3125824 + 17255716 = 1768^2 + 4154^2 .

It is not an unprimeable number, because it can be changed into a prime (20381549) 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, 509519 + ... + 509558.

It is an arithmetic number, because the mean of its divisors is an integer number (3566773).

Almost surely, 2^20381540 is an apocalyptic number.

20381540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20381540 is an abundant number, since it is smaller than the sum of its proper divisors (22419736).

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

20381540 is a wasteful number, since it uses less digits than its factorization.

20381540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1019086 (or 1019084 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 20381540 is about 4514.5918973923. The cubic root of 20381540 is about 273.1569984346.

Adding to 20381540 its reverse (4518302), we get a palindrome (24899842).

The spelling of 20381540 in words is "twenty million, three hundred eighty-one thousand, five hundred forty".