20011220021 has 8 divisors (see below), whose sum is σ = 21551697720. Its totient is φ = 18470907072.

The previous prime is 20011219997. The next prime is 20011220027. The reversal of 20011220021 is 12002211002.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 805140625 + 19206079396 = 28375^2 + 138586^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20011220021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20011219984 and 20011220011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20011220027) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 345851 + ... + 399543.

It is an arithmetic number, because the mean of its divisors is an integer number (2693962215).

Almost surely, 2^20011220021 is an apocalyptic number.

It is an amenable number.

20011220021 is a deficient number, since it is larger than the sum of its proper divisors (1540477699).

20011220021 is a wasteful number, since it uses less digits than its factorization.

20011220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82375.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 20011220021 its reverse (12002211002), we get a palindrome (32013431023).

The spelling of 20011220021 in words is "twenty billion, eleven million, two hundred twenty thousand, twenty-one".