442715821 has 2 divisors, whose sum is σ = 442715822. Its totient is φ = 442715820.

The previous prime is 442715813. The next prime is 442715851. The reversal of 442715821 is 128517244.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 404412100 + 38303721 = 20110^2 + 6189^2 .

It is a cyclic number.

It is not a de Polignac number, because 442715821 - 2³ = 442715813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (442715851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 221357910 + 221357911.

It is an arithmetic number, because the mean of its divisors is an integer number (221357911).

Almost surely, 2^442715821 is an apocalyptic number.

It is an amenable number.

442715821 is a deficient number, since it is larger than the sum of its proper divisors (1).

442715821 is an equidigital number, since it uses as much as digits as its factorization.

442715821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17920, while the sum is 34.

The square root of 442715821 is about 21040.8132209760. The cubic root of 442715821 is about 762.1521529396.

The spelling of 442715821 in words is "four hundred forty-two million, seven hundred fifteen thousand, eight hundred twenty-one".