1991828 has 6 divisors (see below), whose sum is σ = 3485706. Its totient is φ = 995912.

The previous prime is 1991819. The next prime is 1991837. The reversal of 1991828 is 8281991.

It is an interprime number because it is at equal distance from previous prime (1991819) and next prime (1991837).

It can be written as a sum of positive squares in only one way, i.e., 1817104 + 174724 = 1348^2 + 418^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1991791 and 1991800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 248975 + ... + 248982.

It is an arithmetic number, because the mean of its divisors is an integer number (580951).

2^1991828 is an apocalyptic number.

It is an amenable number.

1991828 is a deficient number, since it is larger than the sum of its proper divisors (1493878).

1991828 is a wasteful number, since it uses less digits than its factorization.

1991828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497961 (or 497959 counting only the distinct ones).

The product of its digits is 10368, while the sum is 38.

The square root of 1991828 is about 1411.3213666632. The cubic root of 1991828 is about 125.8202694896.

The spelling of 1991828 in words is "one million, nine hundred ninety-one thousand, eight hundred twenty-eight".