20011221021 has 32 divisors (see below), whose sum is σ = 30651264000. Its totient is φ = 11485169280.

The previous prime is 20011221017. The next prime is 20011221023. The reversal of 20011221021 is 12012211002.

It is not a de Polignac number, because 20011221021 - 2² = 20011221017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20011220988 and 20011221006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20011221023) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2206905 + ... + 2215953.

It is an arithmetic number, because the mean of its divisors is an integer number (957852000).

Almost surely, 2^20011221021 is an apocalyptic number.

It is an amenable number.

20011221021 is a deficient number, since it is larger than the sum of its proper divisors (10640042979).

20011221021 is a wasteful number, since it uses less digits than its factorization.

20011221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12609.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 20011221021 its reverse (12012211002), we get a palindrome (32023432023).

The spelling of 20011221021 in words is "twenty billion, eleven million, two hundred twenty-one thousand, twenty-one".