1990081 has 2 divisors, whose sum is σ = 1990082. Its totient is φ = 1990080.

The previous prime is 1990069. The next prime is 1990103. The reversal of 1990081 is 1800991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1795600 + 194481 = 1340^2 + 441^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990081 - 2¹¹ = 1988033 is a prime.

It is a super-2 number, since 2×1990081² = 7920844773122, which contains 22 as substring.

1990081 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1990031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995040 + 995041.

It is an arithmetic number, because the mean of its divisors is an integer number (995041).

2^1990081 is an apocalyptic number.

It is an amenable number.

1990081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990081 is an equidigital number, since it uses as much as digits as its factorization.

1990081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 1990081 is about 1410.7023073633. The cubic root of 1990081 is about 125.7834737580.

It can be divided in two parts, 19 and 90081, that added together give a triangular number (90100 = T₄₂₄).

The spelling of 1990081 in words is "one million, nine hundred ninety thousand, eighty-one".