1661990 has 32 divisors (see below), whose sum is σ = 3382560. Its totient is φ = 582400.

The previous prime is 1661983. The next prime is 1662007. The reversal of 1661990 is 991661.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2930 + ... + 3450.

It is an arithmetic number, because the mean of its divisors is an integer number (105705).

2^1661990 is an apocalyptic number.

1661990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1661990 is an abundant number, since it is smaller than the sum of its proper divisors (1720570).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661990 is a wasteful number, since it uses less digits than its factorization.

1661990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 1661990 is about 1289.1819111359. The cubic root of 1661990 is about 118.4521102339.

The spelling of 1661990 in words is "one million, six hundred sixty-one thousand, nine hundred ninety".