1991045 has 16 divisors (see below), whose sum is σ = 2755200. Its totient is φ = 1353024.

The previous prime is 1991027. The next prime is 1991047. The reversal of 1991045 is 5401991.

It is a cyclic number.

It is not a de Polignac number, because 1991045 - 2⁶ = 1990981 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1990999 and 1991017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5531 + ... + 5879.

It is an arithmetic number, because the mean of its divisors is an integer number (172200).

2^1991045 is an apocalyptic number.

1991045 is the 815-th octagonal number.

It is an amenable number.

1991045 is a deficient number, since it is larger than the sum of its proper divisors (764155).

1991045 is a wasteful number, since it uses less digits than its factorization.

1991045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 1991045 is about 1411.0439397836. The cubic root of 1991045 is about 125.8037804181.

The spelling of 1991045 in words is "one million, nine hundred ninety-one thousand, forty-five".