409842821 has 4 divisors (see below), whose sum is σ = 420919692. Its totient is φ = 398765952.

The previous prime is 409842791. The next prime is 409842857. The reversal of 409842821 is 128248904.

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

It can be written as a sum of positive squares in 2 ways, for example, as 149181796 + 260661025 = 12214^2 + 16145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-409842821 is a prime.

It is a super-2 number, since 2×409842821² = 335942275850476082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (409842721) 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, 5538380 + ... + 5538453.

It is an arithmetic number, because the mean of its divisors is an integer number (105229923).

Almost surely, 2^409842821 is an apocalyptic number.

It is an amenable number.

409842821 is a deficient number, since it is larger than the sum of its proper divisors (11076871).

409842821 is a wasteful number, since it uses less digits than its factorization.

409842821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11076870.

The product of its (nonzero) digits is 36864, while the sum is 38.

The square root of 409842821 is about 20244.5751005053. The cubic root of 409842821 is about 742.8009389765.

The spelling of 409842821 in words is "four hundred nine million, eight hundred forty-two thousand, eight hundred twenty-one".