1918421221 has 4 divisors (see below), whose sum is σ = 1963035712. Its totient is φ = 1873806732.

The previous prime is 1918421209. The next prime is 1918421243. The reversal of 1918421221 is 1221248191.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1918421221 - 2⁵ = 1918421189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918421261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22307181 + ... + 22307266.

It is an arithmetic number, because the mean of its divisors is an integer number (490758928).

Almost surely, 2^1918421221 is an apocalyptic number.

It is an amenable number.

1918421221 is a deficient number, since it is larger than the sum of its proper divisors (44614491).

1918421221 is an equidigital number, since it uses as much as digits as its factorization.

1918421221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44614490.

The product of its digits is 2304, while the sum is 31.

The square root of 1918421221 is about 43799.7856273293. The cubic root of 1918421221 is about 1242.5522399756.

The spelling of 1918421221 in words is "one billion, nine hundred eighteen million, four hundred twenty-one thousand, two hundred twenty-one".