1721228239 has 4 divisors (see below), whose sum is σ = 1725222240. Its totient is φ = 1717234240.

The previous prime is 1721228177. The next prime is 1721228251. The reversal of 1721228239 is 9328221271.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1721228239 - 2⁷ = 1721228111 is a prime.

It is a super-2 number, since 2×1721228239² = 5925253301462082242, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1721228198 and 1721228207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721228539) 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, 1996354 + ... + 1997215.

It is an arithmetic number, because the mean of its divisors is an integer number (431305560).

Almost surely, 2^1721228239 is an apocalyptic number.

1721228239 is a deficient number, since it is larger than the sum of its proper divisors (3994001).

1721228239 is an equidigital number, since it uses as much as digits as its factorization.

1721228239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3994000.

The product of its digits is 24192, while the sum is 37.

The square root of 1721228239 is about 41487.6878001173. The cubic root of 1721228239 is about 1198.4304106176.

It can be divided in two parts, 17212 and 28239, that added together give a triangular number (45451 = T₃₀₁).

The spelling of 1721228239 in words is "one billion, seven hundred twenty-one million, two hundred twenty-eight thousand, two hundred thirty-nine".