1990451 has 4 divisors (see below), whose sum is σ = 1996032. Its totient is φ = 1984872.

The previous prime is 1990447. The next prime is 1990453. The reversal of 1990451 is 1540991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1540991 = 43 ⋅35837.

It is a cyclic number.

It is not a de Polignac number, because 1990451 - 2² = 1990447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1990453) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2216 + ... + 2981.

It is an arithmetic number, because the mean of its divisors is an integer number (499008).

2^1990451 is an apocalyptic number.

1990451 is a deficient number, since it is larger than the sum of its proper divisors (5581).

1990451 is an equidigital number, since it uses as much as digits as its factorization.

1990451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5580.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 1990451 is about 1410.8334416224. The cubic root of 1990451 is about 125.7912685833.

The spelling of 1990451 in words is "one million, nine hundred ninety thousand, four hundred fifty-one".