1640881 has 12 divisors (see below), whose sum is σ = 1838592. Its totient is φ = 1463000.

The previous prime is 1640879. The next prime is 1640887. The reversal of 1640881 is 1880461.

It is not a de Polignac number, because 1640881 - 2¹ = 1640879 is a prime.

It is a super-2 number, since 2×1640881² = 5384980912322, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640887) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8496 + ... + 8686.

It is an arithmetic number, because the mean of its divisors is an integer number (153216).

2^1640881 is an apocalyptic number.

1640881 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1640881 is a deficient number, since it is larger than the sum of its proper divisors (197711).

1640881 is a wasteful number, since it uses less digits than its factorization.

1640881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 1640881 is about 1280.9687740144. The cubic root of 1640881 is about 117.9484836887.

The spelling of 1640881 in words is "one million, six hundred forty thousand, eight hundred eighty-one".