1213321020 has 96 divisors (see below), whose sum is σ = 3500679168. Its totient is φ = 313765632.

The previous prime is 1213320967. The next prime is 1213321051. The reversal of 1213321020 is 201233121.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 849547 + ... + 850973.

It is an arithmetic number, because the mean of its divisors is an integer number (36465408).

Almost surely, 2^1213321020 is an apocalyptic number.

1213321020 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 1213321020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1750339584).

1213321020 is an abundant number, since it is smaller than the sum of its proper divisors (2287358148).

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

1213321020 is a wasteful number, since it uses less digits than its factorization.

1213321020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1859 (or 1857 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 1213321020 is about 34832.7578580853. The cubic root of 1213321020 is about 1066.5762460246.

Adding to 1213321020 its reverse (201233121), we get a palindrome (1414554141).

It can be divided in two parts, 12133 and 21020, that added together give a triangular number (33153 = T₂₅₇).

The spelling of 1213321020 in words is "one billion, two hundred thirteen million, three hundred twenty-one thousand, twenty".