1681990 has 32 divisors (see below), whose sum is σ = 3234816. Its totient is φ = 628320.

The previous prime is 1681973. The next prime is 1681991. The reversal of 1681990 is 991861.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681991) 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, 16279 + ... + 16381.

It is an arithmetic number, because the mean of its divisors is an integer number (101088).

2^1681990 is an apocalyptic number.

1681990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1681990 is a deficient number, since it is larger than the sum of its proper divisors (1552826).

1681990 is a wasteful number, since it uses less digits than its factorization.

1681990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204.

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 1681990 is about 1296.9155716545. The cubic root of 1681990 is about 118.9253586482.

The spelling of 1681990 in words is "one million, six hundred eighty-one thousand, nine hundred ninety".