1649991 has 8 divisors (see below), whose sum is σ = 2514304. Its totient is φ = 942840.

The previous prime is 1649987. The next prime is 1649993. The reversal of 1649991 is 1999461.

1649991 = 46² + 47² + ... + 171².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1649991 - 2² = 1649987 is a prime.

It is a Duffinian number.

1649991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1649993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39265 + ... + 39306.

It is an arithmetic number, because the mean of its divisors is an integer number (314288).

2^1649991 is an apocalyptic number.

1649991 is a deficient number, since it is larger than the sum of its proper divisors (864313).

1649991 is an equidigital number, since it uses as much as digits as its factorization.

1649991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78581.

The product of its digits is 17496, while the sum is 39.

The square root of 1649991 is about 1284.5197546165. The cubic root of 1649991 is about 118.1663601980.

The spelling of 1649991 in words is "one million, six hundred forty-nine thousand, nine hundred ninety-one".