1231989920 has 96 divisors (see below), whose sum is σ = 3359615616. Its totient is φ = 418176000.

The previous prime is 1231989877. The next prime is 1231989937. The reversal of 1231989920 is 299891321.

It is a happy number.

It is a super-3 number, since 3×1231989920³ (a number of 28 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107675 + ... + 118565.

It is an arithmetic number, because the mean of its divisors is an integer number (34995996).

Almost surely, 2^1231989920 is an apocalyptic number.

1231989920 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 1231989920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1679807808).

1231989920 is an abundant number, since it is smaller than the sum of its proper divisors (2127625696).

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

1231989920 is a wasteful number, since it uses less digits than its factorization.

1231989920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11014 (or 11006 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 1231989920 is about 35099.7139589484. The cubic root of 1231989920 is about 1072.0187584896.

The spelling of 1231989920 in words is "one billion, two hundred thirty-one million, nine hundred eighty-nine thousand, nine hundred twenty".