1823840721 has 6 divisors (see below), whose sum is σ = 2634436610. Its totient is φ = 1215893808.

The previous prime is 1823840693. The next prime is 1823840749. The reversal of 1823840721 is 1270483281.

1823840721 is a `hidden beast` number, since 18 + 238 + 407 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (1823840693) and next prime (1823840749).

It can be written as a sum of positive squares in only one way, i.e., 1753934400 + 69906321 = 41880^2 + 8361^2 .

It is not a de Polignac number, because 1823840721 - 2⁹ = 1823840209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1823840021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 101324476 + ... + 101324493.

Almost surely, 2^1823840721 is an apocalyptic number.

It is an amenable number.

1823840721 is a deficient number, since it is larger than the sum of its proper divisors (810595889).

1823840721 is a wasteful number, since it uses less digits than its factorization.

1823840721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202648975 (or 202648972 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 1823840721 is about 42706.4482367710. The cubic root of 1823840721 is about 1221.7873829949.

The spelling of 1823840721 in words is "one billion, eight hundred twenty-three million, eight hundred forty thousand, seven hundred twenty-one".