2221816821 has 16 divisors (see below), whose sum is σ = 3386572800. Its totient is φ = 1269254448.

The previous prime is 2221816799. The next prime is 2221816823. The reversal of 2221816821 is 1286181222.

It is not a de Polignac number, because 2221816821 - 2⁵ = 2221816789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2221816823) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74620 + ... + 100058.

It is an arithmetic number, because the mean of its divisors is an integer number (211660800).

Almost surely, 2^2221816821 is an apocalyptic number.

2221816821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2221816821 is a deficient number, since it is larger than the sum of its proper divisors (1164755979).

2221816821 is a wasteful number, since it uses less digits than its factorization.

2221816821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29608.

The product of its digits is 6144, while the sum is 33.

The square root of 2221816821 is about 47136.1519536756. The cubic root of 2221816821 is about 1304.8765209572.

The spelling of 2221816821 in words is "two billion, two hundred twenty-one million, eight hundred sixteen thousand, eight hundred twenty-one".