1649881 has 4 divisors (see below), whose sum is σ = 1690164. Its totient is φ = 1609600.

The previous prime is 1649863. The next prime is 1649887. The reversal of 1649881 is 1889461.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1889461 = 7 ⋅269923.

It can be written as a sum of positive squares in 2 ways, for example, as 99856 + 1550025 = 316^2 + 1245^2 .

It is a cyclic number.

It is not a de Polignac number, because 1649881 - 2⁹ = 1649369 is a prime.

It is a super-2 number, since 2×1649881² = 5444214628322, which contains 22 as substring.

It is a Duffinian number.

1649881 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1649881.

It is not an unprimeable number, because it can be changed into a prime (1649887) 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 3 ways as a sum of consecutive naturals, for example, 20080 + ... + 20161.

It is an arithmetic number, because the mean of its divisors is an integer number (422541).

2^1649881 is an apocalyptic number.

It is an amenable number.

1649881 is a deficient number, since it is larger than the sum of its proper divisors (40283).

1649881 is an equidigital number, since it uses as much as digits as its factorization.

1649881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40282.

The product of its digits is 13824, while the sum is 37.

The square root of 1649881 is about 1284.4769363441. The cubic root of 1649881 is about 118.1637342062.

The spelling of 1649881 in words is "one million, six hundred forty-nine thousand, eight hundred eighty-one".