1321202020 has 72 divisors (see below), whose sum is σ = 2923256952. Its totient is φ = 501396480.

The previous prime is 1321202017. The next prime is 1321202027. The reversal of 1321202020 is 202021231.

It can be written as a sum of positive squares in 4 ways, for example, as 681314404 + 639887616 = 26102^2 + 25296^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321202027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1018012 + ... + 1019308.

It is an arithmetic number, because the mean of its divisors is an integer number (40600791).

Almost surely, 2^1321202020 is an apocalyptic number.

1321202020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1321202020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1461628476).

1321202020 is an abundant number, since it is smaller than the sum of its proper divisors (1602054932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1321202020 is a wasteful number, since it uses less digits than its factorization.

1321202020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1421 (or 1388 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 1321202020 is about 36348.3427407633. The cubic root of 1321202020 is about 1097.2941815465.

Adding to 1321202020 its reverse (202021231), we get a palindrome (1523223251).

The spelling of 1321202020 in words is "one billion, three hundred twenty-one million, two hundred two thousand, twenty".