191989780 has 12 divisors (see below), whose sum is σ = 403178580. Its totient is φ = 76795904.

The previous prime is 191989769. The next prime is 191989841. The reversal of 191989780 is 87989191.

It can be written as a sum of positive squares in 2 ways, for example, as 47941776 + 144048004 = 6924^2 + 12002^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4799725 + ... + 4799764.

It is an arithmetic number, because the mean of its divisors is an integer number (33598215).

Almost surely, 2^191989780 is an apocalyptic number.

191989780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

191989780 is an abundant number, since it is smaller than the sum of its proper divisors (211188800).

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

191989780 is a wasteful number, since it uses less digits than its factorization.

191989780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9599498 (or 9599496 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 52.

The square root of 191989780 is about 13856.0376731589. The cubic root of 191989780 is about 576.8895919756.

The spelling of 191989780 in words is "one hundred ninety-one million, nine hundred eighty-nine thousand, seven hundred eighty".