1990305 has 32 divisors (see below), whose sum is σ = 3697920. Its totient is φ = 1013760.

The previous prime is 1990279. The next prime is 1990319. The reversal of 1990305 is 5030991.

1990305 = 115² + 116² + ... + 195².

It is not a de Polignac number, because 1990305 - 2⁵ = 1990273 is a prime.

It is a super-2 number, since 2×1990305² = 7922627986050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an Ulam number.

It is a Curzon number.

1990305 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2785 + ... + 3425.

It is an arithmetic number, because the mean of its divisors is an integer number (115560).

2^1990305 is an apocalyptic number.

1990305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1990305 is a deficient number, since it is larger than the sum of its proper divisors (1707615).

1990305 is a wasteful number, since it uses less digits than its factorization.

1990305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 672 counting only the distinct ones).

The product of its (nonzero) digits is 1215, while the sum is 27.

The square root of 1990305 is about 1410.7816982085. The cubic root of 1990305 is about 125.7881929028.

The spelling of 1990305 in words is "one million, nine hundred ninety thousand, three hundred five".