991554 has 16 divisors (see below), whose sum is σ = 2017440. Its totient is φ = 324800.

The previous prime is 991547. The next prime is 991567. The reversal of 991554 is 455199.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991554.

It is an unprimeable number.

991554 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, 1047 + ... + 1754.

It is an arithmetic number, because the mean of its divisors is an integer number (126090).

2⁹⁹¹⁵⁵⁴ is an apocalyptic number.

991554 is an abundant number, since it is smaller than the sum of its proper divisors (1025886).

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

991554 is a wasteful number, since it uses less digits than its factorization.

991554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2865.

The product of its digits is 8100, while the sum is 33.

The square root of 991554 is about 995.7680452796. The cubic root of 991554 is about 99.7176703163.

It can be divided in two parts, 99 and 1554, that added together give a triangular number (1653 = T₅₇).

The spelling of 991554 in words is "nine hundred ninety-one thousand, five hundred fifty-four".