2021010809 has 2 divisors, whose sum is σ = 2021010810. Its totient is φ = 2021010808.

The previous prime is 2021010799. The next prime is 2021010821. The reversal of 2021010809 is 9080101202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1999878400 + 21132409 = 44720^2 + 4597^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2021010809 is a prime.

It is not a weakly prime, because it can be changed into another prime (2021010889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010505404 + 1010505405.

It is an arithmetic number, because the mean of its divisors is an integer number (1010505405).

Almost surely, 2^2021010809 is an apocalyptic number.

It is an amenable number.

2021010809 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021010809 is an equidigital number, since it uses as much as digits as its factorization.

2021010809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 2021010809 is about 44955.6538046106. The cubic root of 2021010809 is about 1264.3176829363.

The spelling of 2021010809 in words is "two billion, twenty-one million, ten thousand, eight hundred nine".