3123220021 has 4 divisors (see below), whose sum is σ = 3123546732. Its totient is φ = 3122893312.

The previous prime is 3123220013. The next prime is 3123220063. The reversal of 3123220021 is 1200223213.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 424936996 + 2698283025 = 20614^2 + 51945^2 .

It is a cyclic number.

It is not a de Polignac number, because 3123220021 - 2³ = 3123220013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 3123219977 and 3123220004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3123220081) 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, 148570 + ... + 168283.

It is an arithmetic number, because the mean of its divisors is an integer number (780886683).

Almost surely, 2^3123220021 is an apocalyptic number.

It is an amenable number.

3123220021 is a deficient number, since it is larger than the sum of its proper divisors (326711).

3123220021 is an equidigital number, since it uses as much as digits as its factorization.

3123220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 326710.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 3123220021 is about 55885.7765536098. The cubic root of 3123220021 is about 1461.7312329108.

Adding to 3123220021 its reverse (1200223213), we get a palindrome (4323443234).

The spelling of 3123220021 in words is "three billion, one hundred twenty-three million, two hundred twenty thousand, twenty-one".