1231513220 has 24 divisors (see below), whose sum is σ = 2955632064. Its totient is φ = 422233056.

The previous prime is 1231513207. The next prime is 1231513237. The reversal of 1231513220 is 223151321.

It is a super-2 number, since 2×1231513220² = 3033249622069536800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 1231513192 and 1231513201.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4398122 + ... + 4398401.

It is an arithmetic number, because the mean of its divisors is an integer number (123151336).

Almost surely, 2^1231513220 is an apocalyptic number.

1231513220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1231513220 is an abundant number, since it is smaller than the sum of its proper divisors (1724118844).

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

1231513220 is a wasteful number, since it uses less digits than its factorization.

1231513220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8796539 (or 8796537 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 1231513220 is about 35092.9226483062. The cubic root of 1231513220 is about 1071.8804734652.

Adding to 1231513220 its reverse (223151321), we get a palindrome (1454664541).

The spelling of 1231513220 in words is "one billion, two hundred thirty-one million, five hundred thirteen thousand, two hundred twenty".