21016420 has 24 divisors (see below), whose sum is σ = 46731384. Its totient is φ = 7911936.

The previous prime is 21016417. The next prime is 21016423. The reversal of 21016420 is 2461012.

It is an interprime number because it is at equal distance from previous prime (21016417) and next prime (21016423).

It can be written as a sum of positive squares in 4 ways, for example, as 7311616 + 13704804 = 2704^2 + 3702^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21016394 and 21016403.

It is not an unprimeable number, because it can be changed into a prime (21016423) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 30567 + ... + 31246.

It is an arithmetic number, because the mean of its divisors is an integer number (1947141).

Almost surely, 2^21016420 is an apocalyptic number.

21016420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21016420 is an abundant number, since it is smaller than the sum of its proper divisors (25714964).

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

21016420 is a wasteful number, since it uses less digits than its factorization.

21016420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61839 (or 61837 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21016420 is about 4584.3669137625. The cubic root of 21016420 is about 275.9643061031.

Adding to 21016420 its reverse (2461012), we get a palindrome (23477432).

The spelling of 21016420 in words is "twenty-one million, sixteen thousand, four hundred twenty".