1991278230 has 16 divisors (see below), whose sum is σ = 4779067824. Its totient is φ = 531007520.

The previous prime is 1991278189. The next prime is 1991278231. The reversal of 1991278230 is 328721991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991278231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33187941 + ... + 33188000.

It is an arithmetic number, because the mean of its divisors is an integer number (298691739).

Almost surely, 2^1991278230 is an apocalyptic number.

1991278230 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991278230 is an abundant number, since it is smaller than the sum of its proper divisors (2787789594).

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

1991278230 is a wasteful number, since it uses less digits than its factorization.

1991278230 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66375951.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 1991278230 is about 44623.7406544991. The cubic root of 1991278230 is about 1258.0869242326.

The spelling of 1991278230 in words is "one billion, nine hundred ninety-one million, two hundred seventy-eight thousand, two hundred thirty".