821247442 has 8 divisors (see below), whose sum is σ = 1232977356. Its totient is φ = 410254992.

The previous prime is 821247391. The next prime is 821247461. The reversal of 821247442 is 244742128.

It can be written as a sum of positive squares in 2 ways, for example, as 591997561 + 229249881 = 24331^2 + 15141^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 821247398 and 821247407.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 181573 + ... + 186040.

Almost surely, 2^821247442 is an apocalyptic number.

821247442 is a deficient number, since it is larger than the sum of its proper divisors (411729914).

821247442 is a wasteful number, since it uses less digits than its factorization.

821247442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368732.

The product of its digits is 28672, while the sum is 34.

The square root of 821247442 is about 28657.4151311663. The cubic root of 821247442 is about 936.4645533160.

The spelling of 821247442 in words is "eight hundred twenty-one million, two hundred forty-seven thousand, four hundred forty-two".