409802685921 has 24 divisors (see below), whose sum is σ = 597481587560. Its totient is φ = 270643804416.

The previous prime is 409802685913. The next prime is 409802685931. The reversal of 409802685921 is 129586208904.

It is a happy number.

409802685921 is a `hidden beast` number, since 40 + 9 + 8 + 0 + 2 + 6 + 8 + 592 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 192138448896 + 217664237025 = 438336^2 + 466545^2 .

It is not a de Polignac number, because 409802685921 - 2³ = 409802685913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (409802685931) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5508645 + ... + 5582541.

Almost surely, 2^409802685921 is an apocalyptic number.

It is an amenable number.

409802685921 is a deficient number, since it is larger than the sum of its proper divisors (187678901639).

409802685921 is a wasteful number, since it uses less digits than its factorization.

409802685921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79665 (or 79662 counting only the distinct ones).

The product of its (nonzero) digits is 2488320, while the sum is 54.

The spelling of 409802685921 in words is "four hundred nine billion, eight hundred two million, six hundred eighty-five thousand, nine hundred twenty-one".