2021821815 has 64 divisors (see below), whose sum is σ = 3744147456. Its totient is φ = 922724352.

The previous prime is 2021821801. The next prime is 2021821819. The reversal of 2021821815 is 5181281202.

2021821815 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2021821815 - 2⁵ = 2021821783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021821819) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 217554 + ... + 226656.

It is an arithmetic number, because the mean of its divisors is an integer number (58502304).

Almost surely, 2^2021821815 is an apocalyptic number.

2021821815 is a deficient number, since it is larger than the sum of its proper divisors (1722325641).

2021821815 is a wasteful number, since it uses less digits than its factorization.

2021821815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9208.

The product of its (nonzero) digits is 2560, while the sum is 30.

The square root of 2021821815 is about 44964.6729666746. The cubic root of 2021821815 is about 1264.4867785356.

The spelling of 2021821815 in words is "two billion, twenty-one million, eight hundred twenty-one thousand, eight hundred fifteen".