1772820221 has 8 divisors (see below), whose sum is σ = 1788492984. Its totient is φ = 1757214720.

The previous prime is 1772820193. The next prime is 1772820223. The reversal of 1772820221 is 1220282771.

It can be written as a sum of positive squares in 4 ways, for example, as 221563225 + 1551256996 = 14885^2 + 39386^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1772820221 - 2¹⁸ = 1772558077 is a prime.

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 (1772820223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36881 + ... + 70041.

It is an arithmetic number, because the mean of its divisors is an integer number (223561623).

Almost surely, 2^1772820221 is an apocalyptic number.

It is an amenable number.

1772820221 is a deficient number, since it is larger than the sum of its proper divisors (15672763).

1772820221 is a wasteful number, since it uses less digits than its factorization.

1772820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33631.

The product of its (nonzero) digits is 6272, while the sum is 32.

The square root of 1772820221 is about 42104.8717015027. The cubic root of 1772820221 is about 1210.2866203965.

The spelling of 1772820221 in words is "one billion, seven hundred seventy-two million, eight hundred twenty thousand, two hundred twenty-one".