691866 has 72 divisors (see below), whose sum is σ = 1915680. Its totient is φ = 176256.

The previous prime is 691843. The next prime is 691871. The reversal of 691866 is 668196.

691866 = T₂₈ + T₂₉ + ... + T₁₆₀.

691866 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Its product of digits (15552) is a multiple of the sum of its prime divisors (48).

It is a self number, because there is not a number n which added to its sum of digits gives 691866.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 36405 + ... + 36423.

2⁶⁹¹⁸⁶⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (957840).

691866 is an abundant number, since it is smaller than the sum of its proper divisors (1223814).

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

691866 is a wasteful number, since it uses less digits than its factorization.

691866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68 (or 48 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 691866 is about 831.7848279453. The cubic root of 691866 is about 88.4451445942.

The spelling of 691866 in words is "six hundred ninety-one thousand, eight hundred sixty-six".