691980 has 48 divisors (see below), whose sum is σ = 2042880. Its totient is φ = 174528.

The previous prime is 691979. The next prime is 691991. The reversal of 691980 is 89196.

It is a happy number.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 691980.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 837 + ... + 1443.

It is an arithmetic number, because the mean of its divisors is an integer number (42560).

2⁶⁹¹⁹⁸⁰ is an apocalyptic number.

691980 is a gapful number since it is divisible by the number (60) 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 691980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1021440).

691980 is an abundant number, since it is smaller than the sum of its proper divisors (1350900).

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

691980 is a wasteful number, since it uses less digits than its factorization.

691980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638 (or 636 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 691980 is about 831.8533524606. The cubic root of 691980 is about 88.4500020824.

The spelling of 691980 in words is "six hundred ninety-one thousand, nine hundred eighty".