21420000 has 360 divisors, whose sum is σ = 92108016. Its totient is φ = 4608000.

The previous prime is 21419939. The next prime is 21420001. The reversal of 21420000 is 2412.

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420001) by changing a digit.

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 59 ways as a sum of consecutive naturals, for example, 1259992 + ... + 1260008.

Almost surely, 2^21420000 is an apocalyptic number.

21420000 is a gapful number since it is divisible by the number (20) 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 21420000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46054008).

21420000 is an abundant number, since it is smaller than the sum of its proper divisors (70688016).

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

21420000 is a wasteful number, since it uses less digits than its factorization.

21420000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 21420000 is about 4628.1745861625. The cubic root of 21420000 is about 277.7195729900.

Adding to 21420000 its reverse (2412), we get a palindrome (21422412).

The spelling of 21420000 in words is "twenty-one million, four hundred twenty thousand".