1001721220 has 12 divisors (see below), whose sum is σ = 2103614604. Its totient is φ = 400688480.

The previous prime is 1001721187. The next prime is 1001721223. The reversal of 1001721220 is 221271001.

1001721220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 371409984 + 630311236 = 19272^2 + 25106^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1001721194 and 1001721203.

It is not an unprimeable number, because it can be changed into a prime (1001721223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25043011 + ... + 25043050.

It is an arithmetic number, because the mean of its divisors is an integer number (175301217).

Almost surely, 2^1001721220 is an apocalyptic number.

1001721220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1001721220 is an abundant number, since it is smaller than the sum of its proper divisors (1101893384).

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

1001721220 is a wasteful number, since it uses less digits than its factorization.

1001721220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50086070 (or 50086068 counting only the distinct ones).

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 1001721220 is about 31649.9797788245. The cubic root of 1001721220 is about 1000.5734111368.

Adding to 1001721220 its reverse (221271001), we get a palindrome (1222992221).

The spelling of 1001721220 in words is "one billion, one million, seven hundred twenty-one thousand, two hundred twenty".