20121220021 has 8 divisors (see below), whose sum is σ = 23023627904. Its totient is φ = 17225799120.

The previous prime is 20121219991. The next prime is 20121220027. The reversal of 20121220021 is 12002212102.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20121220021 - 2⁷ = 20121219893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121219983 and 20121220010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121220027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1740570 + ... + 1752091.

It is an arithmetic number, because the mean of its divisors is an integer number (2877953488).

Almost surely, 2^20121220021 is an apocalyptic number.

It is an amenable number.

20121220021 is a deficient number, since it is larger than the sum of its proper divisors (2902407883).

20121220021 is an equidigital number, since it uses as much as digits as its factorization.

20121220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3493491.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 20121220021 its reverse (12002212102), we get a palindrome (32123432123).

The spelling of 20121220021 in words is "twenty billion, one hundred twenty-one million, two hundred twenty thousand, twenty-one".