72221220 has 120 divisors (see below), whose sum is σ = 229198200. Its totient is φ = 19035648.

The previous prime is 72221197. The next prime is 72221239. The reversal of 72221220 is 2212227.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 27625536 + 44595684 = 5256^2 + 6678^2 .

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 = 72221193 and 72221202.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 176376 + ... + 176784.

It is an arithmetic number, because the mean of its divisors is an integer number (1909985).

Almost surely, 2^72221220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 72221220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114599100).

72221220 is an abundant number, since it is smaller than the sum of its proper divisors (156976980).

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

72221220 is a wasteful number, since it uses less digits than its factorization.

72221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 539 (or 528 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 72221220 is about 8498.3068901988. The cubic root of 72221220 is about 416.4423994896.

Adding to 72221220 its reverse (2212227), we get a palindrome (74433447).

The spelling of 72221220 in words is "seventy-two million, two hundred twenty-one thousand, two hundred twenty".