1618326221 has 4 divisors (see below), whose sum is σ = 1648860732. Its totient is φ = 1587791712.

The previous prime is 1618326187. The next prime is 1618326233. The reversal of 1618326221 is 1226238161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1226238161 = 251 ⋅4885411.

It can be written as a sum of positive squares in 2 ways, for example, as 1473484996 + 144841225 = 38386^2 + 12035^2 .

It is a cyclic number.

It is not a de Polignac number, because 1618326221 - 2²² = 1614131917 is a prime.

It is a super-2 number, since 2×1618326221² = 5237959515152281682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1618325221) 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, 15267176 + ... + 15267281.

It is an arithmetic number, because the mean of its divisors is an integer number (412215183).

Almost surely, 2^1618326221 is an apocalyptic number.

It is an amenable number.

1618326221 is a deficient number, since it is larger than the sum of its proper divisors (30534511).

1618326221 is an equidigital number, since it uses as much as digits as its factorization.

1618326221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30534510.

The product of its digits is 6912, while the sum is 32.

The square root of 1618326221 is about 40228.4255346888. The cubic root of 1618326221 is about 1174.0556700508.

The spelling of 1618326221 in words is "one billion, six hundred eighteen million, three hundred twenty-six thousand, two hundred twenty-one".