21436020 has 36 divisors (see below), whose sum is σ = 65023140. Its totient is φ = 5716224.

The previous prime is 21436013. The next prime is 21436021. The reversal of 21436020 is 2063412.

It is a happy number.

21436020 is a `hidden beast` number, since 21 + 43 + 602 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16744464 + 4691556 = 4092^2 + 2166^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21435984 and 21436002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21436021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59365 + ... + 59724.

Almost surely, 2^21436020 is an apocalyptic number.

21436020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21436020 is an abundant number, since it is smaller than the sum of its proper divisors (43587120).

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

21436020 is a wasteful number, since it uses less digits than its factorization.

21436020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119104 (or 119099 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21436020 is about 4629.9049666273. The cubic root of 21436020 is about 277.7887911485.

Adding to 21436020 its reverse (2063412), we get a palindrome (23499432).

The spelling of 21436020 in words is "twenty-one million, four hundred thirty-six thousand, twenty".