20011220001 has 24 divisors (see below), whose sum is σ = 29909603880. Its totient is φ = 12877433856.

The previous prime is 20011219997. The next prime is 20011220027. The reversal of 20011220001 is 10002211002.

It can be written as a sum of positive squares in 4 ways, for example, as 2738952225 + 17272267776 = 52335^2 + 131424^2 .

It is not a de Polignac number, because 20011220001 - 2² = 20011219997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (20011220051) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1349041 + ... + 1363793.

It is an arithmetic number, because the mean of its divisors is an integer number (1246233495).

Almost surely, 2^20011220001 is an apocalyptic number.

It is an amenable number.

20011220001 is a deficient number, since it is larger than the sum of its proper divisors (9898383879).

20011220001 is a wasteful number, since it uses less digits than its factorization.

20011220001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19985 (or 19982 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 20011220001 its reverse (10002211002), we get a palindrome (30013431003).

The spelling of 20011220001 in words is "twenty billion, eleven million, two hundred twenty thousand, one".