21424001220 has 216 divisors, whose sum is σ = 67259372544. Its totient is φ = 5519722752.

The previous prime is 21424001213. The next prime is 21424001233. The reversal of 21424001220 is 2210042412.

21424001220 is a `hidden beast` number, since 2 + 1 + 42 + 400 + 1 + 220 = 666.

It is a super-2 number, since 2×21424001220² (a number of 21 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 21424001193 and 21424001202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 55937149 + ... + 55937531.

It is an arithmetic number, because the mean of its divisors is an integer number (311385984).

Almost surely, 2^21424001220 is an apocalyptic number.

21424001220 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 21424001220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33629686272).

21424001220 is an abundant number, since it is smaller than the sum of its proper divisors (45835371324).

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

21424001220 is a wasteful number, since it uses less digits than its factorization.

21424001220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699 (or 657 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 21424001220 its reverse (2210042412), we get a palindrome (23634043632).

The spelling of 21424001220 in words is "twenty-one billion, four hundred twenty-four million, one thousand, two hundred twenty".