21406020 has 48 divisors (see below), whose sum is σ = 60274368. Its totient is φ = 5676160.

The previous prime is 21406001. The next prime is 21406037. The reversal of 21406020 is 2060412.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10915 + ... + 12725.

It is an arithmetic number, because the mean of its divisors is an integer number (1255716).

Almost surely, 2^21406020 is an apocalyptic number.

21406020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21406020 is an abundant number, since it is smaller than the sum of its proper divisors (38868348).

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

21406020 is a wasteful number, since it uses less digits than its factorization.

21406020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2020 (or 2018 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21406020 is about 4626.6640249752. The cubic root of 21406020 is about 277.6591409235.

Adding to 21406020 its reverse (2060412), we get a palindrome (23466432).

The spelling of 21406020 in words is "twenty-one million, four hundred six thousand, twenty".