290991561 has 32 divisors (see below), whose sum is σ = 467539968. Its totient is φ = 157386240.

The previous prime is 290991553. The next prime is 290991563. The reversal of 290991561 is 165199092.

It is a happy number.

It is not a de Polignac number, because 290991561 - 2³ = 290991553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (290991563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43746 + ... + 49956.

It is an arithmetic number, because the mean of its divisors is an integer number (14610624).

Almost surely, 2^290991561 is an apocalyptic number.

290991561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

290991561 is a deficient number, since it is larger than the sum of its proper divisors (176548407).

290991561 is a wasteful number, since it uses less digits than its factorization.

290991561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6341.

The product of its (nonzero) digits is 43740, while the sum is 42.

The square root of 290991561 is about 17058.4747559681. The cubic root of 290991561 is about 662.6641328705.

The spelling of 290991561 in words is "two hundred ninety million, nine hundred ninety-one thousand, five hundred sixty-one".