821724945 has 16 divisors (see below), whose sum is σ = 1315440000. Its totient is φ = 438026624.

The previous prime is 821724931. The next prime is 821724989. The reversal of 821724945 is 549427128.

It is a cyclic number.

It is not a de Polignac number, because 821724945 - 2²² = 817530641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 821724897 and 821724906.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18181 + ... + 44429.

It is an arithmetic number, because the mean of its divisors is an integer number (82215000).

Almost surely, 2^821724945 is an apocalyptic number.

It is an amenable number.

821724945 is a deficient number, since it is larger than the sum of its proper divisors (493715055).

821724945 is a wasteful number, since it uses less digits than its factorization.

821724945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28344.

The product of its digits is 161280, while the sum is 42.

The square root of 821724945 is about 28665.7451499172. The cubic root of 821724945 is about 936.6460162844.

The spelling of 821724945 in words is "eight hundred twenty-one million, seven hundred twenty-four thousand, nine hundred forty-five".