20091000 has 128 divisors (see below), whose sum is σ = 64733760. Its totient is φ = 5184000.

The previous prime is 20090977. The next prime is 20091023. The reversal of 20091000 is 19002.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20090977) and next prime (20091023).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110910 + ... + 111090.

Almost surely, 2^20091000 is an apocalyptic number.

20091000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20091000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32366880).

20091000 is an abundant number, since it is smaller than the sum of its proper divisors (44642760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20091000 is a wasteful number, since it uses less digits than its factorization.

20091000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 228 counting only the distinct ones).

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 20091000 is about 4482.2985175019. The cubic root of 20091000 is about 271.8528255134.

The spelling of 20091000 in words is "twenty million, ninety-one thousand".