691890 has 16 divisors (see below), whose sum is σ = 1660608. Its totient is φ = 184496.

The previous prime is 691877. The next prime is 691891. The reversal of 691890 is 98196.

It is a happy number.

691890 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (691891) by changing a digit.

691890 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11502 + ... + 11561.

It is an arithmetic number, because the mean of its divisors is an integer number (103788).

2⁶⁹¹⁸⁹⁰ is an apocalyptic number.

691890 is an abundant number, since it is smaller than the sum of its proper divisors (968718).

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

691890 is a wasteful number, since it uses less digits than its factorization.

691890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23073.

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

The square root of 691890 is about 831.7992546282. The cubic root of 691890 is about 88.4461672677.

The spelling of 691890 in words is "six hundred ninety-one thousand, eight hundred ninety".