1231189920 has 72 divisors (see below), whose sum is σ = 4201440516. Its totient is φ = 328316928.

The previous prime is 1231189909. The next prime is 1231189937. The reversal of 1231189920 is 299811321.

It can be written as a sum of positive squares in 2 ways, for example, as 1228642704 + 2547216 = 35052^2 + 1596^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 426057 + ... + 428936.

Almost surely, 2^1231189920 is an apocalyptic number.

1231189920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1231189920 is an abundant number, since it is smaller than the sum of its proper divisors (2970250596).

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

1231189920 is a wasteful number, since it uses less digits than its factorization.

1231189920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 855014 (or 855003 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 1231189920 is about 35088.3160040490. The cubic root of 1231189920 is about 1071.7866676550.

The spelling of 1231189920 in words is "one billion, two hundred thirty-one million, one hundred eighty-nine thousand, nine hundred twenty".