20405380 has 12 divisors (see below), whose sum is σ = 42851340. Its totient is φ = 8162144.

The previous prime is 20405353. The next prime is 20405383. The reversal of 20405380 is 8350402.

It can be written as a sum of positive squares in 2 ways, for example, as 16112196 + 4293184 = 4014^2 + 2072^2 .

It is not an unprimeable number, because it can be changed into a prime (20405383) 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, 510115 + ... + 510154.

It is an arithmetic number, because the mean of its divisors is an integer number (3570945).

Almost surely, 2^20405380 is an apocalyptic number.

20405380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20405380 is an abundant number, since it is smaller than the sum of its proper divisors (22445960).

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

20405380 is a wasteful number, since it uses less digits than its factorization.

20405380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020278 (or 1020276 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 20405380 is about 4517.2314530030. The cubic root of 20405380 is about 273.2634595667.

Adding to 20405380 its reverse (8350402), we get a palindrome (28755782).

The spelling of 20405380 in words is "twenty million, four hundred five thousand, three hundred eighty".