21065420 has 12 divisors (see below), whose sum is σ = 44237424. Its totient is φ = 8426160.

The previous prime is 21065417. The next prime is 21065423. The reversal of 21065420 is 2456012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21065417) and next prime (21065423).

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1053271 = 21065420 / (2 + 1 + 0 + 6 + 5 + 4 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 21065392 and 21065401.

It is not an unprimeable number, because it can be changed into a prime (21065423) 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, 526616 + ... + 526655.

It is an arithmetic number, because the mean of its divisors is an integer number (3686452).

Almost surely, 2^21065420 is an apocalyptic number.

21065420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21065420 is an abundant number, since it is smaller than the sum of its proper divisors (23172004).

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

21065420 is a wasteful number, since it uses less digits than its factorization.

21065420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053280 (or 1053278 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21065420 is about 4589.7080517175. The cubic root of 21065420 is about 276.1786108467.

The spelling of 21065420 in words is "twenty-one million, sixty-five thousand, four hundred twenty".