821406161 has 4 divisors (see below), whose sum is σ = 821628324. Its totient is φ = 821184000.

The previous prime is 821406133. The next prime is 821406193. The reversal of 821406161 is 161604128.

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 270799936 + 550606225 = 16456^2 + 23465^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821406161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821405161) 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, 105440 + ... + 112961.

It is an arithmetic number, because the mean of its divisors is an integer number (205407081).

Almost surely, 2^821406161 is an apocalyptic number.

It is an amenable number.

821406161 is a deficient number, since it is larger than the sum of its proper divisors (222163).

821406161 is a wasteful number, since it uses less digits than its factorization.

821406161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222162.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 821406161 is about 28660.1842457441. The cubic root of 821406161 is about 936.5248782703.

The spelling of 821406161 in words is "eight hundred twenty-one million, four hundred six thousand, one hundred sixty-one".