1991010 has 64 divisors (see below), whose sum is σ = 5760000. Its totient is φ = 430272.

The previous prime is 1990987. The next prime is 1991027. The reversal of 1991010 is 101991.

1991010 is a nontrivial binomial coefficient, being equal to C(1996, 2).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3741 + ... + 4239.

It is an arithmetic number, because the mean of its divisors is an integer number (90000).

2^1991010 is an apocalyptic number.

1991010 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991010 is the 1995-th triangular number and also the 998-th hexagonal number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991010, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2880000).

1991010 is an abundant number, since it is smaller than the sum of its proper divisors (3768990).

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

1991010 is a wasteful number, since it uses less digits than its factorization.

1991010 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535.

The product of its (nonzero) digits is 81, while the sum is 21.

The square root of 1991010 is about 1411.0315375639. The cubic root of 1991010 is about 125.8030432577.

The spelling of 1991010 in words is "one million, nine hundred ninety-one thousand, ten".