20090091 has 16 divisors (see below), whose sum is σ = 30841344. Its totient is φ = 11394624.

The previous prime is 20090071. The next prime is 20090093. The reversal of 20090091 is 19009002.

It is a happy number.

It is not a de Polignac number, because 20090091 - 2⁶ = 20090027 is a prime.

It is a super-2 number, since 2×20090091² = 807223512776562, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (20090093) 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 15 ways as a sum of consecutive naturals, for example, 615 + ... + 6368.

It is an arithmetic number, because the mean of its divisors is an integer number (1927584).

Almost surely, 2^20090091 is an apocalyptic number.

20090091 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20090091 is a deficient number, since it is larger than the sum of its proper divisors (10751253).

20090091 is a wasteful number, since it uses less digits than its factorization.

20090091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7130.

The product of its (nonzero) digits is 162, while the sum is 21.

The square root of 20090091 is about 4482.1971174860. The cubic root of 20090091 is about 271.8487255359.

Adding to 20090091 its reverse (19009002), we get a palindrome (39099093).

It can be divided in two parts, 2009009 and 1, that added together give a triangular number (2009010 = T₂₀₀₄).

The spelling of 20090091 in words is "twenty million, ninety thousand, ninety-one".