1231720866 has 24 divisors (see below), whose sum is σ = 2809188720. Its totient is φ = 388964376.

The previous prime is 1231720859. The next prime is 1231720877. The reversal of 1231720866 is 6680271321.

It is a self number, because there is not a number n which added to its sum of digits gives 1231720866.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1800420 + ... + 1801103.

It is an arithmetic number, because the mean of its divisors is an integer number (117049530).

Almost surely, 2^1231720866 is an apocalyptic number.

1231720866 is an abundant number, since it is smaller than the sum of its proper divisors (1577467854).

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

1231720866 is a wasteful number, since it uses less digits than its factorization.

1231720866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3601550 (or 3601547 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 1231720866 is about 35095.8810403728. The cubic root of 1231720866 is about 1071.9407134965.

The spelling of 1231720866 in words is "one billion, two hundred thirty-one million, seven hundred twenty thousand, eight hundred sixty-six".