1243199920 has 20 divisors (see below), whose sum is σ = 2890440000. Its totient is φ = 497279936.

The previous prime is 1243199917. The next prime is 1243199957. The reversal of 1243199920 is 299913421.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7769920 + ... + 7770079.

It is an arithmetic number, because the mean of its divisors is an integer number (144522000).

Almost surely, 2^1243199920 is an apocalyptic number.

1243199920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1243199920 is an abundant number, since it is smaller than the sum of its proper divisors (1647240080).

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

1243199920 is a wasteful number, since it uses less digits than its factorization.

1243199920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15540012 (or 15540006 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 1243199920 is about 35259.0402592016. The cubic root of 1243199920 is about 1075.2604150065.

The spelling of 1243199920 in words is "one billion, two hundred forty-three million, one hundred ninety-nine thousand, nine hundred twenty".