821423709 has 24 divisors (see below), whose sum is σ = 1227343104. Its totient is φ = 528840000.

The previous prime is 821423671. The next prime is 821423737. The reversal of 821423709 is 907324128.

It is not a de Polignac number, because 821423709 - 2¹⁶ = 821358173 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821423749) 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 23 ways as a sum of consecutive naturals, for example, 142534 + ... + 148184.

It is an arithmetic number, because the mean of its divisors is an integer number (51139296).

Almost surely, 2^821423709 is an apocalyptic number.

It is an amenable number.

821423709 is a deficient number, since it is larger than the sum of its proper divisors (405919395).

821423709 is a wasteful number, since it uses less digits than its factorization.

821423709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6209 (or 6206 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 821423709 is about 28660.4903831041. The cubic root of 821423709 is about 936.5315473305.

The spelling of 821423709 in words is "eight hundred twenty-one million, four hundred twenty-three thousand, seven hundred nine".