21420516 has 48 divisors (see below), whose sum is σ = 54732608. Its totient is φ = 6480000.

The previous prime is 21420499. The next prime is 21420541. The reversal of 21420516 is 61502412.

It is a junction number, because it is equal to n+sod(n) for n = 21420492 and 21420501.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8391 + ... + 10641.

Almost surely, 2^21420516 is an apocalyptic number.

21420516 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27366304).

21420516 is an abundant number, since it is smaller than the sum of its proper divisors (33312092).

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

21420516 is a wasteful number, since it uses less digits than its factorization.

21420516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2332 (or 2330 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21420516 is about 4628.2303313470. The cubic root of 21420516 is about 277.7218030265.

Adding to 21420516 its reverse (61502412), we get a palindrome (82922928).

The spelling of 21420516 in words is "twenty-one million, four hundred twenty thousand, five hundred sixteen".