1821421216 has 12 divisors (see below), whose sum is σ = 3585923082. Its totient is φ = 910710592.

The previous prime is 1821421211. The next prime is 1821421309. The reversal of 1821421216 is 6121241281.

It can be written as a sum of positive squares in only one way, i.e., 986211216 + 835210000 = 31404^2 + 28900^2 .

It is not an unprimeable number, because it can be changed into a prime (1821421211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28459675 + ... + 28459738.

Almost surely, 2^1821421216 is an apocalyptic number.

1821421216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1821421216 is a deficient number, since it is larger than the sum of its proper divisors (1764501866).

1821421216 is an equidigital number, since it uses as much as digits as its factorization.

1821421216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56919423 (or 56919415 counting only the distinct ones).

The product of its digits is 1536, while the sum is 28.

The square root of 1821421216 is about 42678.1116733156. Note that the first 3 decimals coincide. The cubic root of 1821421216 is about 1221.2468699980.

Adding to 1821421216 its reverse (6121241281), we get a palindrome (7942662497).

The spelling of 1821421216 in words is "one billion, eight hundred twenty-one million, four hundred twenty-one thousand, two hundred sixteen".