991690 has 32 divisors (see below), whose sum is σ = 2110464. Its totient is φ = 328320.

The previous prime is 991663. The next prime is 991693. The reversal of 991690 is 96199.

It is a happy number.

991690 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×991690³ = 2925829783331427000, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991693) by changing a digit.

991690 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 15 ways as a sum of consecutive naturals, for example, 1942 + ... + 2398.

It is an arithmetic number, because the mean of its divisors is an integer number (65952).

2⁹⁹¹⁶⁹⁰ is an apocalyptic number.

991690 is an abundant number, since it is smaller than the sum of its proper divisors (1118774).

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

991690 is a wasteful number, since it uses less digits than its factorization.

991690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 991690 is about 995.8363319341. The cubic root of 991690 is about 99.7222291479.

It can be divided in two parts, 991 and 690, that added together give a square (1681 = 41²).

The spelling of 991690 in words is "nine hundred ninety-one thousand, six hundred ninety".