21420630 has 144 divisors (see below), whose sum is σ = 70211232. Its totient is φ = 4435200.

The previous prime is 21420587. The next prime is 21420643. The reversal of 21420630 is 3602412.

It is a happy number.

21420630 is a `hidden beast` number, since 2 + 14 + 20 + 630 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

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 71 ways as a sum of consecutive naturals, for example, 76090 + ... + 76370.

It is an arithmetic number, because the mean of its divisors is an integer number (487578).

Almost surely, 2^21420630 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420630, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35105616).

21420630 is an abundant number, since it is smaller than the sum of its proper divisors (48790602).

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

21420630 is a wasteful number, since it uses less digits than its factorization.

21420630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21420630 is about 4628.2426470530. The cubic root of 21420630 is about 277.7222957042.

The spelling of 21420630 in words is "twenty-one million, four hundred twenty thousand, six hundred thirty".