1991764 has 12 divisors (see below), whose sum is σ = 3496500. Its totient is φ = 992768.

The previous prime is 1991761. The next prime is 1991779. The reversal of 1991764 is 4671991.

It can be written as a sum of positive squares in 2 ways, for example, as 478864 + 1512900 = 692^2 + 1230^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1242 + ... + 2350.

It is an arithmetic number, because the mean of its divisors is an integer number (291375).

2^1991764 is an apocalyptic number.

It is an amenable number.

1991764 is a deficient number, since it is larger than the sum of its proper divisors (1504736).

1991764 is a wasteful number, since it uses less digits than its factorization.

1991764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1562 (or 1560 counting only the distinct ones).

The product of its digits is 13608, while the sum is 37.

The square root of 1991764 is about 1411.2986926941. The cubic root of 1991764 is about 125.8189218860.

The spelling of 1991764 in words is "one million, nine hundred ninety-one thousand, seven hundred sixty-four".