391980 has 48 divisors (see below), whose sum is σ = 1128960. Its totient is φ = 101568.

The previous prime is 391967. The next prime is 391987. The reversal of 391980 is 89193.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (391987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2751 + ... + 2889.

It is an arithmetic number, because the mean of its divisors is an integer number (23520).

2³⁹¹⁹⁸⁰ is an apocalyptic number.

391980 is a gapful number since it is divisible by the number (30) 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 391980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (564480).

391980 is an abundant number, since it is smaller than the sum of its proper divisors (736980).

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

391980 is a wasteful number, since it uses less digits than its factorization.

391980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 391980 is about 626.0830615821. The cubic root of 391980 is about 73.1848695175.

The spelling of 391980 in words is "three hundred ninety-one thousand, nine hundred eighty".