4221637728 has 216 divisors, whose sum is σ = 14171436216. Its totient is φ = 1096381440.

The previous prime is 4221637723. The next prime is 4221637747. The reversal of 4221637728 is 8277361224.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 4221637728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4221637723) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 565476 + ... + 572892.

It is an arithmetic number, because the mean of its divisors is an integer number (65608501).

Almost surely, 2^4221637728 is an apocalyptic number.

4221637728 is a gapful number since it is divisible by the number (48) 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 4221637728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7085718108).

4221637728 is an abundant number, since it is smaller than the sum of its proper divisors (9949798488).

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

4221637728 is a wasteful number, since it uses less digits than its factorization.

4221637728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7466 (or 7440 counting only the distinct ones).

The product of its digits is 225792, while the sum is 42.

The square root of 4221637728 is about 64974.1312215869. The cubic root of 4221637728 is about 1616.1946102587.

The spelling of 4221637728 in words is "four billion, two hundred twenty-one million, six hundred thirty-seven thousand, seven hundred twenty-eight".