21380418 has 12 divisors (see below), whose sum is σ = 46324278. Its totient is φ = 7126800.

The previous prime is 21380399. The next prime is 21380423. The reversal of 21380418 is 81408312.

It can be written as a sum of positive squares in only one way, i.e., 19210689 + 2169729 = 4383^2 + 1473^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21380391 and 21380400.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 593883 + ... + 593918.

Almost surely, 2^21380418 is an apocalyptic number.

21380418 is an abundant number, since it is smaller than the sum of its proper divisors (24943860).

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

21380418 is a wasteful number, since it uses less digits than its factorization.

21380418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1187809 (or 1187806 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21380418 is about 4623.8964088742. The cubic root of 21380418 is about 277.5484015890.

The spelling of 21380418 in words is "twenty-one million, three hundred eighty thousand, four hundred eighteen".