20091009 has 8 divisors (see below), whose sum is σ = 26943552. Its totient is φ = 13316240.

The previous prime is 20090977. The next prime is 20091023. The reversal of 20091009 is 90019002.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20091009 - 2⁵ = 20090977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20098009) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18837 + ... + 19874.

It is an arithmetic number, because the mean of its divisors is an integer number (3367944).

Almost surely, 2^20091009 is an apocalyptic number.

It is an amenable number.

20091009 is a deficient number, since it is larger than the sum of its proper divisors (6852543).

20091009 is a wasteful number, since it uses less digits than its factorization.

20091009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38887.

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

The square root of 20091009 is about 4482.2995214510. The cubic root of 20091009 is about 271.8528661067.

The spelling of 20091009 in words is "twenty million, ninety-one thousand, nine".